2024-03-28T16:19:19Zhttp://digital.csic.es/dspace-oai/requestoai:digital.csic.es:10261/27892020-03-12T09:59:17Zcom_10261_10252com_10261_3com_10261_28com_10261_4col_10261_10253col_10261_281
2008-01-30T15:32:12Z
urn:hdl:10261/2789
Optical waveguide cantilever actuated by light
Zinoviev, Kirill
Domínguez, Carlos
Plaza, José Antonio
Lechuga, Laura M.
Bending
Cantilevers
micromechanical devices
optical modulation
optical waveguides
We present experimental studies and theoretical analysis of a microcantilever working as an optical waveguide metallized from one side and actuated by light propagating inside it. Light absorbed in
the metallic layer increases the temperature of the bimetallic structure and induces the cantilever bending. Dynamical properties of the cantilevers were studied using actuation by light modulated at frequencies of up to 800 Hz. The deflection of the cantilever by 400 nm was obtained while 0.25 mW of light power was coupled inside it.© 2008 American Institute of Physics.
2008-01-30T15:32:12Z
2008-01-30T15:32:12Z
2008-01-04
artículo
APPLIED PHYSICS LETTERS 92, 011908, 2008
0003-6951
http://hdl.handle.net/10261/2789
10.1063/1.2830818
eng
openAccess
American Institute of Physics
oai:digital.csic.es:10261/103132019-02-25T10:27:47Zcom_10261_10252com_10261_3col_10261_10253
2009-02-05T08:48:58Z
urn:hdl:10261/10313
Supramolecular control of the magnetic anisotropy in two-dimensional high-spin Fe arrays at a metal interface
Gambardella, Pietro
Stepanow, Sebastian
Dmitriev, Alexandre
Honolka, J.
Groot, Frank M. F. de
Lingenfelder, Magalí
Gupta, Subhra Sen
Sarma, D. D.
Bencok, Peter
Stanescu, Stefan
Clair, Sylvain
Pons, Stéphane
Lin, Nian
Seitsonen, Ari P.
Brune, H.
Barth, Johannes V.
Kern, Klaus
European Science Foundation
Ministerio de Educación y Ciencia (España)
5 pages, 3 figures.-- Supplementary information (Sample preparation, Suppl. figures S1-S6, tables S1-S3, 17 pages) available at: http://www.nature.com/nmat/journal/vaop/ncurrent/extref/nmat2376-s1.pdf
Article in press.
Magnetic atoms at surfaces are a rich model system for solid-state magnetic bits exhibiting either classical or quantum behaviour. Individual atoms, however, are difficult to arrange in regular patterns. Moreover, their magnetic properties are dominated by interaction with the substrate,
which, as in the case of Kondo systems, often leads to a decrease or quench of their local magnetic moment. Here, we show that the supramolecular assembly of Fe and
1,4-benzenedicarboxylic acid molecules on a Cu surface results in ordered arrays of high-spin mononuclear Fe centres on a
1.5nm square grid. Lateral coordination with the molecular ligands yields unsaturated yet stable coordination bonds,
which enable chemical modification of the electronic and magnetic properties of the Fe atoms independently from the substrate. The easy magnetization direction of the Fe centres can be switched by oxygen adsorption, thus opening a way to control the magnetic anisotropy in supramolecular layers akin to that used in metallic thin films.
2009-02-05T08:48:58Z
2009-02-05T08:48:58Z
2009-02-01
artículo
Nature Materials, doi: 10.1038/nmat2376 (In Press)
1476-1122
http://hdl.handle.net/10261/10313
10.1038/nmat2376
1476-4660
http://dx.doi.org/10.13039/501100000782
eng
http://dx.doi.org/10.1038/nmat2376
openAccess
Nature Publishing Group
oai:digital.csic.es:10261/103572018-01-23T07:18:04Zcom_10261_10252com_10261_3col_10261_10253
2009-02-05T13:05:15Z
urn:hdl:10261/10357
Magnetic properties of ultrathin FexCo(1-x) films on Pt(111)
Moulas, Géraud
Lehnert, Anne
Rusponi, S.
Etzkorn, Markus
Bencok, Peter
Gambardella, Pietro
Weinberger, P.
Brune, H.
Swiss National Science Foundation
Austrian Science Fund
Department of Energy (US)
European Science Foundation
Ab initio calculations
Band structure
Cobalt alloys
Ferromagnetic materials
Iron alloys
Kerr magneto-optical effect
Magnetic anisotropy
Magnetic circular dichroism
Magnetic moments
Magnetic thin films
Monolayers
14 pages, 14 figures.-- PACS nrs.: 75.70.Ak; 75.30.Gw; 73.20.At.
et al.
The magnetism of 1-ML-thick films of Fe(x)Co(1−x) on Pt(111) was investigated both experimentally, by x-ray magnetic circular dichroism and magneto-optical Kerr effect measurements, and theoretically, by first-principles electronic structure calculations, as a function of the film chemical composition. The calculated Fe and Co spin moments are only weakly dependent on the composition and close to 3µ(B)/atom and 2µ(B)/atom, respectively. This trend is also seen in the experimental data, except for pure Fe, where an effective spin moment of only Seff=(1.2 ± 0.2) µ(B)/atom was measured. On the other hand, both the orbital moment and the magnetic anisotropy energy show a strong composition dependence with maxima close to the Fe(0.5)Co(0.5) stoichiometry. The experiment, in agreement with theory, gives a maximum magnetic anisotropy energy of 0.5 meV/atom, which is more than 2 orders of magnitude larger than the value observed in bulk bcc FeCo and close to that observed for the L10 phase of FePt. The calculations clearly demonstrate that this composition dependence is the result of a fine tuning in the occupation number of the d(x^2−y^2) and d(xy) orbitals due to the Fe-Co electronic hybridization.
2009-02-05T13:05:15Z
2009-02-05T13:05:15Z
2008-12-17
artículo
Physical Review B 78: 214424 (2008)
1098-0121
http://hdl.handle.net/10261/10357
10.1103/PhysRevB.78.214424
http://dx.doi.org/10.13039/501100002428
http://dx.doi.org/10.13039/501100000782
http://dx.doi.org/10.13039/100000015
eng
http://dx.doi.org/10.1103/PhysRevB.78.214424
openAccess
American Physical Society
oai:digital.csic.es:10261/103592016-02-16T04:23:37Zcom_10261_10252com_10261_3col_10261_10253
2009-02-05T13:28:41Z
urn:hdl:10261/10359
Kondo Effect in Single Atom Contacts: The Importance of the Atomic Geometry
Vitali, Lucia
Ohmann, Robin
Stepanow, Sebastian
Gambardella, Pietro
Tao, Kun
Huang, Renzhong
Stepanyuk, Valeri S.
Bruno, Patrick
Kern, Klaus
German Research Foundation
[PACS] Nanoscale contacts (electronic transport)
[PACS] Scanning tunneling microscopy of surfaces, interfaces and thin films
[PACS] Basis sets and related methodology (condensed matter electronic structure)
[PACS] Surface impurity and defect levels; energy states of adsorbed species
4 pages, 3 figures.-- PACS nrs.: 73.63.Rt; 68.37.Ef; 71.15.Ap; 73.20.Hb.-- ArXiv pre-print available at: http://arxiv.org/abs/0808.0585
Contains Electronic Physics Auxiliary Publication for "Kondo effect in single
adatom contacts: the importance of the atomic geometry" (2 extra pages, 1 EPAPS figure).
Co single atom junctions on copper surfaces are studied by scanning tunneling microscopy and ab initio calculations. The Kondo temperature of single cobalt atoms on the Cu(111) surface has been measured at various tip-sample distances ranging from tunneling to the point contact regime. The experiments show a constant Kondo temperature for a whole range of tip-substrate distances consistently with the predicted energy position of the spin-polarized d levels of Co. This is in striking difference to experiments on Co/Cu(100) junctions, where a substantial increase of the Kondo temperature has been found. Our calculations reveal that the different behavior of the Co adatoms on the two Cu surfaces originates from the interplay between the structural relaxations and the electronic properties in the near-contact regime.
2009-02-05T13:28:41Z
2009-02-05T13:28:41Z
2008-11-18
artículo
Physical Review Letters 101, 216802 (2008)
0031-9007
http://hdl.handle.net/10261/10359
10.1103/PhysRevLett.101.216802
http://dx.doi.org/10.13039/501100001659
eng
http://dx.doi.org/10.1103/PhysRevLett.101.216802
openAccess
American Physical Society
oai:digital.csic.es:10261/103612016-02-16T04:36:48Zcom_10261_10252com_10261_3col_10261_10253
2009-02-05T13:45:53Z
urn:hdl:10261/10361
Element-resolved x-ray ferrimagnetic and ferromagnetic resonance spectroscopy
Boero, G.
Mouaziz, S.
Rusponi, S.
Bencok, Peter
Nolting, F.
Stepanow, Sebastian
Gambardella, Pietro
16 pages, 8 figures.-- ArXiv pre-print available at: http://arxiv.org/abs/0704.3139
We report on the measurement of element-specific magnetic resonance spectra at gigahertz frequencies using x-ray magnetic circular dichroism (XMCD). We investigate the ferrimagnetic precession of Gd and Fe ions in Gd-substituted yttrium iron garnet, showing that the resonant field and linewidth of Gd precisely coincide with Fe up to the nonlinear regime of parametric excitations. The opposite sign of the Gd x-ray magnetic resonance signal with respect to Fe is consistent with dynamic antiferromagnetic alignment of the two ionic species. Further, we investigate a bilayer metal film, Ni(80)Fe(20)(5 nm)/Ni(50 nm), where the coupled resonance modes of Ni and Ni(80)Fe(20) are separately resolved, revealing shifts in the resonance fields of individual layers but no mutual driving effects. Energy-dependent dynamic XMCD measurements are introduced, combining x-ray absorption and magnetic resonance spectroscopies.
2009-02-05T13:45:53Z
2009-02-05T13:45:53Z
2008-01-17
artículo
New Journal of Physics 10: 01301 (2008)
1367-2630
http://hdl.handle.net/10261/10361
10.1088/1367-2630/10/1/013011
eng
http://dx.doi.org/10.1088/1367-2630/10/1/013011
openAccess
Institute of Physics Publishing
Deutsche Physikalische Gesellschaft
oai:digital.csic.es:10261/103622009-02-05T14:01:03Zcom_10261_10252com_10261_3col_10261_10253
2009-02-05T14:00:33Z
urn:hdl:10261/10362
Modular assembly of low-dimensional coordination architectures on metal surfaces
Stepanow, Sebastian
Lin, Nian
Barth, Johannes V.
15 pages, 12 figures.
The engineering of highly organized molecular architectures has attracted strong interest because of its potential for novel materials and functional nanoscopic devices. An important factor in the development, integration, and exploitation of such systems is the capability to prepare them on surfaces or in nanostructured environments. Recent advances in supramolecular design on metal substrates provide atomistic insight into the underlying self-assembly processes, mainly by scanning tunneling microscopy observations. This review summarizes progress in noncovalent synthesis strategies under ultra-high vacuum conditions employing metal ions as coordination centers directing the molecular organization. The realized metallosupramolecular compounds and arrays combine the properties of their constituent metal ions and organic ligands, and present several attractive features: their redox, magnetic and spin-state transitions. The presented exemplary molecular level studies elucidate the arrangement of organic adsorbates on metal surfaces, demonstrating the interplay between intermolecular and molecule–substrate interactions that needs to be controlled for the fabrication of low-dimensional structures. The understanding of metallosupramolecular organization and metal–ligand interactions on solid surfaces is important for the control of structure and concomitant function.
2009-02-05T14:00:33Z
2009-02-05T14:00:33Z
2008-04-17
artículo
Journal of Physics: Condensed Matter 20: 184002 (2008)
0953-8984
http://hdl.handle.net/10261/10362
10.1088/0953-8984/20/18/184002
eng
http://dx.doi.org/10.1088/0953-8984/20/18/184002
closedAccess
Institute of Physics Publishing
oai:digital.csic.es:10261/104282016-02-16T04:28:18Zcom_10261_10252com_10261_3col_10261_10253
2009-02-09T10:20:11Z
urn:hdl:10261/10428
Absence of local magnetic moments in Ru and Rh impurities and clusters on Ag(100) and Pt(997)
Honolka, J.
Kuhnke, K.
Vitali, Lucia
Enders, A.
Kern, Klaus
Gardonio, S.
Carbone, Carlo
Krishnakumar, S. R.
Bencok, Peter
Stepanow, Sebastian
Gambardella, Pietro
Atomic clusters
Impurities
Local moments
Magnetic circular dichroism
Monolayers
Platinum
Rhodium
Ruthenium
Silver
X-ray spectra
6 pages, 5 figures.-- PACS nrs.: 75.20.Hr; 78.20.Ls; 78.70.Dm.-- ArXiv pre-print available at: http://arxiv.org/abs/0708.3975
The magnetism of quench-condensed Ru and Rh impurities and metal films on Ag(100) and Pt(997) has been studied using x-ray magnetic circular dichroism. In the coverage range between 0.22 and 2.0 ML, no dichroic signal was detected at the M(3,2) absorption edges of Ru on Ag(100) at a temperature of 5 K in the presence of an applied magnetic field. The same was found for coverages between 0.12 and 0.5 ML of Rh on Ag(100) and Pt(997). It is concluded that the magnetic moments of single impurities, small clusters of various shape, and monolayers of the 4d metals are below the detection limit of 0.04 µB per atom. These results provide an unambiguous determination of the local magnetic moment of Ru and Rh deposited on nonmagnetic transition-metal surfaces, which are in contrast with theoretical predictions.
2009-02-09T10:20:11Z
2009-02-09T10:20:11Z
2007-10-09
artículo
Physical Review B 76(14): 144412 (2007)
1098-0121
http://hdl.handle.net/10261/10428
10.1103/PhysRevB.76.144412
eng
http://dx.doi.org/10.1103/PhysRevB.76.144412
openAccess
American Physical Society
oai:digital.csic.es:10261/104312016-02-16T04:28:20Zcom_10261_10252com_10261_3col_10261_10253
2009-02-09T10:35:47Z
urn:hdl:10261/10431
Surface characterization of Mn(x)Ge(1−x) and Cr(y)Mn(x)Ge(1−x−y) dilute magnetic semiconductors
Gambardella, Pietro
Claude, L.
Rusponi, S.
Franke, K. J.
Brune, H.
Raabe, J.
Nolting, F.
Bencok, Peter
Hanbicki, A. T.
Jonker, B. T.
Grazioli, C.
Veronese, M.
Carbone, Carlo
Swiss National Science Foundation
Ministero dell'Istruzione, dell'Università e della Ricerca
Office of Naval Research (US)
Manganese compounds
Chromium compounds
Semimagnetic semiconductors
Ferromagnetic materials
Paramagnetic materials
Magnetic moments
X-ray photoelectron spectra
X-ray absorption
Semiconductor epitaxial layers
Fluorescence
Etching
Surface composition
Magnetic circular dichroism
Oxidation
Segregation
7 pages, 7 figures.-- PACS nrs.: 75.50.Pp; 75.70.-i; 78.70.Dm; 75.20.Hr.
We have used x-ray photoemission electron microscopy (XPEEM) and x-ray absorption spectroscopy (XAS) to characterize Mn(x)Ge(1−x) and Cr(y)Mn(x)Ge(1−x−y) films grown by molecular beam epitaxy. The surface layers of the as-grown films probed by XPEEM present segregation of Mn-rich phases. XAS using both total electron yield and fluorescence yield detection shows that the films are heavily oxidized after exposure to air. Etching in HF and HCl can be used to reduce oxidation, but inhomogeneities in the surface composition might not be completely eliminated depending on the Mn concentration. X-ray magnetic circular dichroism (XMCD) measurements reveal that neither the etched nor the as-grown films present remanent ferromagnetic behavior down to a temperature of 5 K within the probing depth of the fluorescence yield (~20 nm). Mn is paramagnetic in both the oxidized and etched samples, with an increased tendency to order magnetically toward the interior of the films. Cr in Cr(y)Mn(x)Ge(1−x−y) possesses a paramagnetic moment only in the oxidized form. A comparison of the XAS line shapes obtained in the present study with those of Mn impurities deposited on Ge and GaAs surfaces demonstrates that the interpretation of XAS spectra of Mn-doped dilute magnetic semiconductors in the literature is often affected by residual oxidation.
2009-02-09T10:35:47Z
2009-02-09T10:35:47Z
2007-03-28
artículo
Physical Review B 75(12): 125211 (2007)
1098-0121
http://hdl.handle.net/10261/10431
10.1103/PhysRevB.75.125211
http://dx.doi.org/10.13039/501100003407
http://dx.doi.org/10.13039/100000006
eng
http://dx.doi.org/10.1103/PhysRevB.75.125211
openAccess
American Physical Society
oai:digital.csic.es:10261/104362016-02-16T04:17:20Zcom_10261_10252com_10261_3col_10261_10253
2009-02-09T10:45:59Z
urn:hdl:10261/10436
Structure and magnetism of atomically thin Fe layers on flat and vicinal Pt surfaces
Repetto, D.
Rusponi, S.
Honolka, J.
Kuhnke, K.
Sessi, V.
Brune, H.
Gambardella, Pietro
Carbone, Carlo
Enders, A.
Kern, Klaus
Iron
Ferromagnetic materials
Magnetic thin films
Metallic thin films
Scanning tunnelling microscopy
Low energy electron diffraction
Kerr magneto-optical effect
Magnetic circular dichroism
Spin dynamics
Magnetic anisotropy
8 pages, 11 figures.-- PACS nrs.: 75.30.Gw; 75.30.Kz; 75.50.Bb; 75.70.Ak.
Ultrathin Fe films on Pt substrates have been investigated under ultrahigh vacuum conditions by scanning tunneling microscopy, low energy electron diffraction, magneto-optical Kerr effect, x-ray magnetic circular dichroism measurements, and Kerr microscopy. We present a comparison between Fe films on flat Pt(111) and stepped Pt(997), with particular focus on the magnetic anisotropy in the submonolayer thickness range below 0.2 monolayer coverage, and above the spin reorientation transition at 3 monolayer thickness. The comparison of structure and magnetism suggests that the perpendicular easy axis found for films thinner than three monolayers is due to dominating contributions from both film interfaces to the anisotropy energy. The Fe-Pt interface contribution has its origin in the hybridization of the Fe 3d with the Pt 5d band. The in-plane magnetic anisotropy above 3 atomic layers film thickness can be correlated directly with peculiarities of the film structure.
2009-02-09T10:45:59Z
2009-02-09T10:45:59Z
2006-08-04
artículo
Physical Review B 74(5): 054408 (2006)
1098-0121
http://hdl.handle.net/10261/10436
10.1103/PhysRevB.74.054408
eng
http://dx.doi.org/10.1103/PhysRevB.74.054408
openAccess
American Physical Society
oai:digital.csic.es:10261/104392016-02-16T04:17:21Zcom_10261_10252com_10261_3col_10261_10253
2009-02-09T10:53:58Z
urn:hdl:10261/10439
Equilibrium island-size distribution in one dimension
Gambardella, Pietro
Brune, H.
Kern, Klaus
Marchenko, V. I.
Phase equilibrium
Island structure
Mesoscopic systems
Quantum wires
Lattice gas
Silver
One-dimensional conductivity
Nucleation
Platinum
4 pages, 2 figures.-- PACS nrs.: 81.16.Dn; 82.60.Nh; 68.55.Ac; 68.43.De.
We derive an analytical expression for the size distribution of monoatomic wires in the framework of a one-dimensional lattice gas model at thermodynamic equilibrium. The theoretical results are compared with the size distribution of one-dimensional Ag wires obtained via nucleation at the step edges of the Pt(997) surface.
2009-02-09T10:53:58Z
2009-02-09T10:53:58Z
2006-06-20
artículo
Physical Review B 73(24): 245425 (2006)
1098-0121
http://hdl.handle.net/10261/10439
10.1103/PhysRevB.73.245425
eng
http://dx.doi.org/10.1103/PhysRevB.73.245425
openAccess
American Physical Society
oai:digital.csic.es:10261/104422019-02-12T08:31:28Zcom_10261_10252com_10261_3col_10261_10253
2009-02-09T11:01:48Z
urn:hdl:10261/10442
Magnetic Nanostructures: Quantum chains with a spin
Gambardella, Pietro
2 pages, 2 figures.
The ability to access experimentally the quantum-mechanical nature of the
interaction between single atomic spins opens windows onto the most fundamental magnetic phenomena.
2009-02-09T11:01:48Z
2009-02-09T11:01:48Z
2006-06
artículo
Nature Materials 5(6): 431-432 (2006)
1476-1122
http://hdl.handle.net/10261/10442
10.1038/nmat1662
1476-4660
eng
http://dx.doi.org/10.1038/nmat1662
closedAccess
Nature Publishing Group
oai:digital.csic.es:10261/104572019-02-25T10:34:52Zcom_10261_10252com_10261_3col_10261_10253
2009-02-09T12:09:02Z
urn:hdl:10261/10457
Finite-sized Heisenberg chains and magnetism of one-dimensional metal systems
Vindigni, A.
Rettori, A.
Pini, M. G.
Carbone, Carlo
Gambardella, Pietro
[PACS] Intrinsic properties of magnetically ordered materials
[PACS] Magnetic anisotropy
[PACS] X-ray absorption spectra
10 pages, 7 figures.-- PACS nrs.: 57.10.Pq; 75.30.-m; 75.30.Gw; 78.70.Dm.-- Published online Oct 22, 2005.
We present a combined experimental and theoretical study of the magnetization of one-dimensional atomic cobalt chains deposited on a platinum surface. We discuss the intrinsic magnetization parameters derived by X-ray magnetic circular dichroism measurements and the observation of ferromagnetic order in one dimension in connection with the presence of strong, dimensionality-dependent anisotropy energy barriers of magnetocrystalline origin. An explicit transfer matrix formalism is developed to treat atomic chains of finite length within the anisotropic Heisenberg model. This model allows us to fit the experimental magnetization curves of cobalt monatomic chains, measured parallel to the easy and hard axes, and provides values of the exchange coupling parameter and the magnetic anisotropy energy consistent with those reported in the literature. The analysis of the spin–spin correlation as a function of temperature provides further insight into the tendency to magnetic order in finite-sized one-dimensional systems.
2009-02-09T12:09:02Z
2009-02-09T12:09:02Z
2006-02
artículo
Applied Physics A: Materials Science & Processing 82(3): 385-394 (2006)
0947-8396
http://hdl.handle.net/10261/10457
10.1007/s00339-005-3364-4
1432-0630
eng
http://dx.doi.org/10.1007/s00339-005-3364-4
closedAccess
Springer
oai:digital.csic.es:10261/104632021-12-27T16:46:18Zcom_10261_10252com_10261_3col_10261_10253
2009-02-09T12:53:07Z
urn:hdl:10261/10463
Atomic force microscopy shows that vaccinia topoisomerase IB generates filaments on DNA in a cooperative fashion
Moreno-Herrero, Fernando
Holtzer, Laurent
Koster, Daniel A.
Shuman, Stewart
Dekker, Cees
Dekker, Nynke H.
Fundación Ramón Areces
Foundation for Fundamental Research on Matter
Netherlands Organization for Scientific Research
National Institutes of Health (US)
9 pages, 6 figures.-- PMID: 16237128 [PubMed].-- PMCID: PMC1258176.
Type IB DNA topoisomerases cleave and rejoin one strand of the DNA duplex, allowing for the removal of supercoils generated during replication and transcription. In addition, electron microscopy of cellular and viral TopIB–DNA complexes has suggested that the enzyme promotes long-range DNA–DNA crossovers and synapses. Here, we have used the atomic force microscope to visualize and quantify the interaction between vaccinia topoisomerase IB (vTopIB) and DNA. vTopIB was found to form filaments on nicked-circular DNA by intramolecular synapsis of two segments of a single DNA molecule. Measuring the filament length as a function of protein concentration showed that synapsis is a highly cooperative process. At high protein:DNA ratios, synapses between distinct DNA molecules were observed, which led to the formation of large vTopIB-induced DNA clusters. These clusters were observed in the presence of Mg2+, Ca2+ or Mn2+, suggesting that the formation of intermolecular vTopIB-mediated DNA synapsis is favored by screening of the DNA charge.
2009-02-09T12:53:07Z
2009-02-09T12:53:07Z
2005-10-19
artículo
Nucleic Acids Research 33(18): 5945-5953 (2005)
0305-1048
http://hdl.handle.net/10261/10463
10.1093/nar/gki906
http://dx.doi.org/10.13039/100008054
http://dx.doi.org/10.13039/100000002
http://dx.doi.org/10.13039/501100001712
16237128
eng
http://dx.doi.org/10.1093/nar/gki906
openAccess
Oxford University Press
oai:digital.csic.es:10261/104642016-06-28T00:46:01Zcom_10261_10252com_10261_3col_10261_10253
2009-02-09T13:06:54Z
urn:hdl:10261/10464
Comment on “Direct and Real-Time Visualization of the Disassembly of a Single RecA-DNA-ATPγS Complex Using AFM Imaging in Fluid”
Heijden, Thijn van der
Moreno-Herrero, Fernando
Kanaar, Roland
Wyman, Claire
Dekker, Cees
3 pages, 1 figure.-- PMID: 17163748 [PubMed].-- Further reply to comment in Nano Lett. 2007 Apr;7(4):1110-1.
Recently, Li et al. published a paper entitled "Direct and real-time visualization of the disassembly of a
single RecA-DNA-ATPγS complex using AFM imaging in fluid" [Nano Lett. 2006, 6, 1474-1478]. They reported the disassembly of RecA from doublestranded (ds) DNA as observed by AFM imaging in deionized water. RecA plays an important role during homologous recombination forming a nucleoprotein filament that drives DNA strand invasion and exchange reactions.
2009-02-09T13:06:54Z
2009-02-09T13:06:54Z
2006-11-11
artículo
Nano Letters 6(12): 3000-3002 (2006)
1530-6984
http://hdl.handle.net/10261/10464
10.1021/nl061746j
eng
http://dx.doi.org/10.1021/nl061746j
closedAccess
American Chemical Society
oai:digital.csic.es:10261/104652021-10-29T07:20:26Zcom_10261_10252com_10261_3com_10261_28com_10261_4com_10261_46col_10261_10253col_10261_281col_10261_299
2009-02-09T13:21:09Z
urn:hdl:10261/10465
Subnanometer Motion of Cargoes Driven by Thermal Gradients Along Carbon Nanotubes
Barreiro, Amelia
Rurali, Riccardo
Hernández, Eduardo R.
Moser, Joel
Pichler, Thomas
Forró, László
Bachtold, Adrian
European Science Foundation
European Commission
Ministerio de Educación y Ciencia (España)
Generalitat de Catalunya
Swiss National Science Foundation
Consejo Superior de Investigaciones Científicas (España)
4 pages, 4 figures.-- Printed version published May 9, 2008.
Supplementary information available at: http://www.sciencemag.org/cgi/content/full/1155559/DC1
An important issue in nanoelectromechanical systems is developing small electrically driven motors. We report on an artificial nanofabricated motor in which one short carbon nanotube moves relative to another coaxial nanotube. A cargo is attached to an ablated outer wall of a multiwalled carbon nanotube that can rotate and/or translate along the inner nanotube. The motion is actuated by imposing a thermal gradient along the nanotube, which allows for subnanometer displacements, as opposed to an electromigration or random walk effect.
2009-02-09T13:21:09Z
2009-02-09T13:21:09Z
2008-04-10
artículo
Science 320(5877): 775-778 (2008)
0036-8075
http://hdl.handle.net/10261/10465
10.1126/science.1155559
1095-9203
http://dx.doi.org/10.13039/501100000782
http://dx.doi.org/10.13039/501100000780
http://dx.doi.org/10.13039/501100002809
http://dx.doi.org/10.13039/501100003339
eng
http://dx.doi.org/10.1126/science.1155559
closedAccess
American Association for the Advancement of Science
oai:digital.csic.es:10261/104672017-03-01T11:50:59Zcom_10261_10252com_10261_3com_10261_28com_10261_4col_10261_10253col_10261_281
2009-02-09T13:36:13Z
urn:hdl:10261/10467
Imaging Mechanical Vibrations in Suspended Graphene Sheets
García-Sánchez, Daniel
Zande, A. M. van der
San Paulo, Álvaro
Lassagne, Benjamin
McEuen, P. L.
Bachtold, Adrian
European Science Foundation
European Commission
National Science Foundation (US)
5 pages, 4 figures.-- Printed version published May 14, 2008.
Supporting information available: A detailed description of fabrication technique, a description of the FEM model, a comparison of the FEM model to analytical predictions
for a beam under tension as well as recent simulations on nanotubes with slack, and a detailed description of the SFM technique to detect mechanical vibrations. Available at: http://pubs.acs.org/doi/suppl/10.1021/nl080201h/suppl_file/nl080201h-file002.pdf
We carried out measurements on nanoelectromechanical systems based on multilayer graphene sheets suspended over trenches in silicon oxide. The motion of the suspended sheets was electrostatically driven at resonance using applied radio frequency voltages. The mechanical vibrations were detected using a novel form of scanning probe microscopy, which allowed identification and spatial imaging of the shape of the mechanical eigenmodes. In as many as half the resonators measured, we observed a new class of exotic nanoscale vibration eigenmodes not predicted by the elastic beam theory, where the amplitude of vibration is maximum at the free edges. By modeling the suspended sheets with the finite element method, these edge eigenmodes are shown to be the result of nonuniform stress with remarkably large magnitudes (up to 1.5 GPa). This nonuniform stress, which arises from the way graphene is prepared by pressing or rubbing bulk graphite against another surface, should be taken into account in future studies on electronic and mechanical properties of graphene.
2009-02-09T13:36:13Z
2009-02-09T13:36:13Z
2008-04-11
artículo
Nano Letters 8(5): 1399-1403 (2008)
1530-6984
http://hdl.handle.net/10261/10467
10.1021/nl080201h
http://dx.doi.org/10.13039/501100000782
http://dx.doi.org/10.13039/501100000780
http://dx.doi.org/10.13039/100000001
eng
http://dx.doi.org/10.1021/nl080201h
closedAccess
American Chemical Society
oai:digital.csic.es:10261/104722016-04-26T10:06:47Zcom_10261_10252com_10261_3com_10261_28com_10261_4col_10261_10253col_10261_281
2009-02-10T08:03:33Z
urn:hdl:10261/10472
The environment of graphene probed by electrostatic force microscopy
Moser, Joel
Verdaguer, Albert
Jiménez, David
Barreiro, Amelia
Bachtold, Adrian
European Science Foundation
European Commission
Ministerio de Educación y Ciencia (España)
Adhesive bonding
Adsorption
Carbon
Electrical conductivity
Micromechanics
3 pages, 3 figures.-- PACS nrs.: 72.80.Rj, 82.65.+r.-- ArXiv pre-print available at: http://arxiv.org/abs/0803.2032
We employ electrostatic force microscopy to study the electrostatic environment of graphene sheets prepared with the micromechanical exfoliation technique. We detect the electric dipole of residues left from the adhesive tape during graphene preparation, as well as the dipole of water molecules adsorbed on top of graphene. Water molecules form a dipole layer that can generate an electric field as large as ~10^9 V m−1. We expect that water molecules can significantly modify the electrical properties of graphene devices.
2009-02-10T08:03:33Z
2009-02-10T08:03:33Z
2008-03-26
artículo
Applied Physics Letters 92, 123507 (2008)
0003-6951
http://hdl.handle.net/10261/10472
10.1063/1.2898501
http://dx.doi.org/10.13039/501100000782
http://dx.doi.org/10.13039/501100000780
eng
http://dx.doi.org/10.1063/1.2898501
openAccess
American Institute of Physics
oai:digital.csic.es:10261/104742009-02-10T10:27:56Zcom_10261_10252com_10261_3com_10261_28com_10261_4col_10261_10253col_10261_281
2009-02-10T08:13:21Z
urn:hdl:10261/10474
Detecting Individual Electrons Using a Carbon Nanotube Field-Effect Transistor
Gruneis, Andreas
Esplandiú, María J.
García-Sánchez, Daniel
Bachtold, Adrian
European Science Foundation
European Commission
4 pages, 4 figures.-- Printed version published Dec 12, 2007.
We study a simple highly resistive molecular circuit by detecting the transfer of individual electrons. The circuit consists of a Au nanoparticle, a carbon nanotube transistor, and a gate electrode, and the tube−particle resistance is about 1019 Ω. The high-impedance measurements are carried out by counting the electrons that are transferred onto the particle using the nanotube transistor as the charge detector. These measurements allow for the electron characterization of the circuit. In addition, single-electron detection is used to determine the separation between the electron states in the particle or to monitor the decay in time of the electron number in the particle.
2009-02-10T08:13:21Z
2009-02-10T08:13:21Z
2007-11-21
artículo
Nano Letters 7(12): 3766-3769 (2007)
1530-6984
http://hdl.handle.net/10261/10474
10.1021/nl072243w
http://dx.doi.org/10.13039/501100000782
http://dx.doi.org/10.13039/501100000780
eng
http://dx.doi.org/10.1021/nl072243w
closedAccess
American Chemical Society
oai:digital.csic.es:10261/104752016-02-16T04:33:26Zcom_10261_10252com_10261_3com_10261_28com_10261_4col_10261_10253col_10261_281
2009-02-10T08:23:52Z
urn:hdl:10261/10475
Current-induced cleaning of graphene
Moser, Joel
Barreiro, Amelia
Bachtold, Adrian
European Science Foundation
European Commission
Adsorption
Carbon
Quantum Hall effect
Surface cleaning
Surface contamination
3 pages, 4 figures.-- PACS nrs.: 81.05.Uw, 81.65.Cf, 68.35.Dv, 68.43.Mn, 73.43.Fj.-- ArXiv pre-print available at: http://arxiv.org/abs/0709.0607
A simple yet highly reproducible method to suppress contamination of graphene at low temperature inside the cryostat is presented. The method consists of applying a current of several milliamperes through the graphene device, which is here typically a few microns wide. This ultrahigh current density is shown to remove contamination adsorbed on the surface. This method is well suited for quantum electron transport studies of undoped graphene devices, and its utility is demonstrated here by measuring the anomalous quantum Hall effect.
2009-02-10T08:23:52Z
2009-02-10T08:23:52Z
2007-10-19
artículo
Applied Physics Letters 91, 163513 (2007)
0003-6951
http://hdl.handle.net/10261/10475
10.1063/1.2789673
http://dx.doi.org/10.13039/501100000782
http://dx.doi.org/10.13039/501100000780
eng
http://dx.doi.org/10.1063/1.2789673
openAccess
American Institute of Physics
oai:digital.csic.es:10261/104772018-05-17T12:00:27Zcom_10261_10252com_10261_3com_10261_28com_10261_4col_10261_10253col_10261_281
2009-02-10T08:39:02Z
urn:hdl:10261/10477
Mechanical detection of carbon nanotube resonator vibrations
García-Sánchez, Daniel
San Paulo, Álvaro
Esplandiú, María J.
Perez Murano, Francesc X.
Forró, László
Aguasca, A.
Bachtold, Adrian
European Science Foundation
European Commission
[PACS] Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
[PACS] Nanotubes (electronic transport)
[PACS] Nanoscale pattern formation in nanofabrication and processing
[PACS] Nanotube devices
4 pages, 3 figures.-- PACS nrs.: 85.85.+j; 73.63.Fg; 81.16.Rf; 85.35.Kt.-- ArXiv pre-print available at: http://arxiv.org/abs/0712.3196
Bending-mode vibrations of carbon nanotube resonators were mechanically detected in air at atmospheric pressure by means of a novel scanning force microscopy method. The fundamental and higher order bending eigenmodes were imaged at up to 3.1 GHz with subnanometer resolution in vibration amplitude. The resonance frequency and the eigenmode shape of multiwall nanotubes are consistent with the elastic beam theory for a doubly clamped beam. For single-wall nanotubes, however, resonance frequencies are significantly shifted, which is attributed to fabrication generating, for example, slack. The effect of slack is studied by pulling down the tube with the tip, which drastically reduces the resonance frequency.
2009-02-10T08:39:02Z
2009-02-10T08:39:02Z
2007-08-20
artículo
Physical Review Letters 99, 085501 (2007)
0031-9007
http://hdl.handle.net/10261/10477
10.1103/PhysRevLett.99.085501
http://dx.doi.org/10.13039/501100000782
http://dx.doi.org/10.13039/501100000780
eng
http://dx.doi.org/10.1103/PhysRevLett.99.085501
openAccess
American Institute of Physics
oai:digital.csic.es:10261/104792019-02-11T16:50:21Zcom_10261_10252com_10261_3com_10261_28com_10261_4col_10261_10253col_10261_281
2009-02-10T08:49:01Z
urn:hdl:10261/10479
Control of the single-wall carbon nanotube mean diameter in sulphur promoted aerosol-assisted chemical vapour deposition
Barreiro, Amelia
Kramberger, Christian
Rümmeli, Mark H.
Grüneis, Alexander
Grimm, D.
Hampel, Silke
Gemming, Thomas
Büchner, Bernd
Bachtold, Adrian
Pichler, Thomas
German Academic Exchange Service
German Research Foundation
International Max Planck Research Schools
Austrian Science Fund
7 pages, 3 figures.-- Online version available Oct 27, 2006.
The influence of gas flow on nanotube diameter during the synthesis of high-purity, very long single-wall carbon nanotubes (SWCNT) via aerosol-assisted chemical vapour deposition is reported. The sample morphology, nanotube yield, defect concentration and amount of carbonaceous impurities, as well as the mean diameter and the diameter distribution of the SWCNTs were analysed by combined scanning- and transmission electron microscopy, Fourier Transform Raman spectroscopy and optical absorption spectroscopy. The results show that by using a solution of ferrocene and sulphur in m-xylene the addition of sulphur as a promoter was found to enhance the SWCNT growth and to increase the yield. A reduction of the mean diameter and a change in the diameter distribution are observed when the total gas flow is increased.
2009-02-10T08:49:01Z
2009-02-10T08:49:01Z
2007-01
artículo
Carbon 45(1): 55-61 (2007)
0008-6223
http://hdl.handle.net/10261/10479
10.1016/j.carbon.2006.08.013
http://dx.doi.org/10.13039/501100001655
http://dx.doi.org/10.13039/501100001659
http://dx.doi.org/10.13039/501100002428
eng
http://dx.doi.org/10.1016/j.carbon.2006.08.013
closedAccess
Elsevier
oai:digital.csic.es:10261/104822019-02-11T16:50:06Zcom_10261_10252com_10261_3com_10261_28com_10261_4col_10261_10253col_10261_281
2009-02-10T09:00:15Z
urn:hdl:10261/10482
Thermal Decomposition of Ferrocene as a Method for Production of Single-Walled Carbon Nanotubes without Additional Carbon Sources
Barreiro, Amelia
Hampel, Silke
Rümmeli, Mark H.
Kramberger, Christian
Grüneis, Alexander
Biedermann, Kati
Leonhardt, Albrecht
Gemming, Thomas
Büchner, Bernd
Bachtold, Adrian
Pichler, Thomas
German Research Foundation
International Max Planck Research Schools
Austrian Science Fund
5 pages, 5 figures.-- Printed version published Oct 26, 2006.
A new method to grow bulk quantities of single-walled carbon nanotubes (SWCNTs) by a catalytic chemical vapor deposition (CVD) process with the possibility of varying the pressure has been developed and is reported in this paper. Thermal decomposition of ferrocene provides both catalytic particles and carbon sources for SWCNT growth using Ar as a carrier gas. Upon an increase in the pressure, the mean diameter of the SWCNTs decreases. In fact, high abundances of SWCNT with diameters as small as 0.7 nm, which is the limit for stable caps with isolated pentagons, can be obtained. An additional advantage of this method is that as no external carbon sources are required, SWCNT synthesis can be achieved at temperatures as low as 650°C.
2009-02-10T09:00:15Z
2009-02-10T09:00:15Z
2006-09-29
artículo
Journal of Physical Chemistry B 110(42): 20973-20977 (2006)
1520-6106
http://hdl.handle.net/10261/10482
10.1021/jp0636571
http://dx.doi.org/10.13039/501100001659
http://dx.doi.org/10.13039/501100002428
eng
http://dx.doi.org/10.1021/jp0636571
closedAccess
American Chemical Society
oai:digital.csic.es:10261/104832016-02-16T04:17:29Zcom_10261_28com_10261_4com_10261_10252com_10261_3col_10261_281col_10261_10253
2009-02-10T09:07:51Z
urn:hdl:10261/10483
Beyond the linearity of current–voltage characteristics in multiwalled carbon nanotubes
Bourlon, Bertrand
Miko, C.
Forró, László
Glattli, D. C.
Bachtold, Adrian
Swiss National Science Foundation
[PACS] Nanotubes
[PACS] High-field and nonlinear effects
[PACS] Scattering by phonons, magnons, and other nonlocalized excitations
5 pages, 5 figures.-- PACS nrs.: 73.63.Fg, 73.50.Fq, 72.10.Di.-- ArXiv pre-print available at: http://arxiv.org/abs/cond-mat/0610519
We present local and non-local electron transport measurements on individual multi-wall nanotubes for bias voltages between 0 and about 4 V. Local current–voltage characteristics are quite linear. In contrast, non-local measurements are highly nonlinear; the differential non-local conductance can even become negative in the high-bias regime. We discuss the relationship between these results and transport parameters such as the elastic length, the number of current carrying shells and the number of conducting modes.
2009-02-10T09:07:51Z
2009-02-10T09:07:51Z
2006-10-17
artículo
Semiconductor Science and Technology 21(11): S33-S37 (2006)
0268-1242
http://hdl.handle.net/10261/10483
10.1088/0268-1242/21/11/S05
eng
http://dx.doi.org/10.1088/0268-1242/21/11/S05
openAccess
Institute of Physics Publishing
oai:digital.csic.es:10261/104962016-02-16T04:17:30Zcom_10261_10252com_10261_3com_10261_28com_10261_4col_10261_10253col_10261_281
2009-02-10T10:20:27Z
urn:hdl:10261/10496
Cotunneling and one-dimensional localization in individual disordered single-wall carbon nanotubes: Temperature dependence of the intrinsic resistance
Gao, B.
Glattli, D. C.
Plaçais, B.
Bachtold, Adrian
Carbon nanotubes
Quantum dots
Coulomb blockade
Kink bands
Hopping conduction
Electrical resistivity
Tunnelling
5 pages, 4 figures.-- PACS nrs.: 73.63.Fg; 73.20.Fz; 73.23.Hk.-- ArXiv pre-print available at: http://arxiv.org/abs/cond-mat/0606473
We report on the temperature dependence of the intrinsic resistance of long individual disordered single-wall carbon nanotubes. The resistance grows dramatically as the temperature is reduced, and the functional form is consistent with an activated behavior. These results are described by a Coulomb blockade along a series of quantum dots. We occasionally observe a kink in the activated behavior that reflects the change of the activation energy as the temperature range is changed. This is attributed to charge hopping events between nonadjacent quantum dots, which is possible through cotunneling processes.
2009-02-10T10:20:27Z
2009-02-10T10:20:27Z
2006-08-15
artículo
Physical Review B 74(8): 085410 (2006)
1098-0121
http://hdl.handle.net/10261/10496
10.1103/PhysRevB.74.085410
eng
http://dx.doi.org/10.1103/PhysRevB.74.085410
openAccess
American Physical Society
oai:digital.csic.es:10261/105012016-02-16T04:28:28Zcom_10261_10252com_10261_3com_10261_28com_10261_4col_10261_10253col_10261_281
2009-02-10T10:42:14Z
urn:hdl:10261/10501
Four-Point Resistance of Individual Single-Wall Carbon Nanotubes
Gao, B.
Chen, Y. F.
Fuhrer, M. S.
Glattli, D. C.
Bachtold, Adrian
National Science Foundation (US)
[PACS] Nanotubes
[PACS] Relaxation times and mean free paths
[PACS] Fullerenes and related materials
[PACS] Electronic transport in mesoscopic systems
4 pages, 5 figures.-- PACS nrs.: 73.63.Fg, 72.15.Lh, 72.80.Rj, 73.23.−b.-- ArXiv pre-print available at: http://arxiv.org/abs/cond-mat/0505041
We have studied the resistance of single-wall carbon nanotubes measured in a four-point configuration with noninvasive voltage electrodes. The voltage drop is detected using multiwalled carbon nanotubes while the current is injected through nanofabricated Au electrodes. The resistance at room temperature is shown to be linear with the length as expected for a classical resistor. This changes at cryogenic temperature; the four-point resistance then depends on the resistance at the Au-tube interfaces and can even become negative due to quantum-interference effects.
2009-02-10T10:42:14Z
2009-02-10T10:42:14Z
2005-10-31
artículo
Physical Review Letters 95(19): 196802 (2005)
0031-9007
http://hdl.handle.net/10261/10501
10.1103/PhysRevLett.95.196802
http://dx.doi.org/10.13039/100000001
eng
http://dx.doi.org/10.1103/PhysRevLett.95.196802
openAccess
American Physical Society
oai:digital.csic.es:10261/152932019-02-13T09:51:24Zcom_10261_10252com_10261_3col_10261_10253
2009-07-24T11:07:18Z
urn:hdl:10261/15293
Coupling Mechanics to Charge Transport in Carbon Nanotube Mechanical Resonators
Lassagne, Benjamin
Tarakanov, Yury
Kinaret, Jari
García-Sánchez, David
Bachtold, Adrian
4 pages, 4 figures.-- Printed version published Aug 28, 2009.-- Supporting information available at: www.sciencemag.org/cgi/content/full/1174290/DC1
Nanoelectromechanical resonators have potential applications in sensing, cooling, and mechanical signal processing. An important parameter in these systems is the strength of coupling the resonator motion to charge transport through the device. We investigate the mechanical oscillations of a suspended single-walled carbon nanotube that also acts as a single-electron transistor. The coupling of the mechanical and the charge degrees of freedom is strikingly strong as well as widely tunable (the associated damping rate is ~ 5 · 10^5 Hz). In particular, the coupling is strong enough to drive the oscillations in the nonlinear regime.
2009-07-24T11:07:18Z
2009-07-24T11:07:18Z
2009-07-23
artículo
Science 325(5944): 1107-1110 (2009)
0036-8075
http://hdl.handle.net/10261/15293
10.1126/science.1174290
1095-9203
eng
http://dx.doi.org/10.1126/science.1174290
closedAccess
American Association for the Advancement of Science
oai:digital.csic.es:10261/153522020-11-12T08:18:47Zcom_10261_10252com_10261_3com_10261_123com_10261_8col_10261_10253col_10261_376
2009-07-26T10:46:35Z
urn:hdl:10261/15352
Nanoparticle-mediated local and remote manipulation of protein aggregation
Kogan, Marcelo J.
Bastús, Neus G.
Amigo, Roger
Grillo-Bosch, Dolors
Araya, Eyleen
Turiel, Antonio
Labarta, Amilcar
Giralt, Ernest
Puntes, Víctor F.
Generalitat de Catalunya
Ministerio de Educación y Ciencia (España)
Universidad de Chile
6 pages, 5 figures.-- PMID: 16402797 [PubMed]
Supporting information available: Additional details on the experimental procedures, nanoparticle conjugation, TEM images, the image analysis, and size exclusion chromatography.-- Available at: http://pubs.acs.org/doi/suppl/10.1021/nl0516862
The local heat delivered by metallic nanoparticles selectively attached to their target can be used as a molecular surgery to safely remove toxic and clogging aggregates. We apply this principle to protein aggregates, in particular to the amyloid beta protein (Aβ) involved in Alzheimer's disease (AD), a neurodegenerative disease where unnaturally folded Aβ proteins self-assemble and deposit forming amyloid fibrils and plaques. We show the possibility to remotely redissolve these deposits and to interfere with their growth, using the local heat dissipated by gold nanoparticles (AuNP) selectively attached to the aggregates and irradiated with low gigahertz electromagnetic fields. Simultaneous tagging and manipulation by AuNP of Aβ at different stages of aggregation allow both, noninvasive exploration and dissolution of molecular aggregates
2009-07-26T10:46:35Z
2009-07-26T10:46:35Z
2006-01-11
artículo
Nano Letters 6(1): 110-115 (2006)
1530-6984
http://hdl.handle.net/10261/15352
10.1021/nl0516862
http://dx.doi.org/10.13039/501100002809
http://dx.doi.org/10.13039/501100005853
eng
https://doi.org/10.1021/nl0516862
closedAccess
American Chemical Society
oai:digital.csic.es:10261/155372020-11-12T10:29:21Zcom_10261_123com_10261_8com_10261_10252com_10261_3col_10261_376col_10261_10253
2009-07-30T11:26:50Z
urn:hdl:10261/15537
Gold nanoparticles for selective and remote heating of β-amyloid protein aggregates
Bastús, Neus G.
Kogan, Marcelo J.
Amigo, Roger
Grillo-Bosch, Dolors
Araya, Eyleen
Turiel, Antonio
Labarta, Amilcar
Giralt, Ernest
Puntes, Víctor F.
Generalitat de Catalunya
Ministerio de Educación y Ciencia (España)
Universidad de Chile
Gold nanoparticles
Protein aggregates
Microwaves
Molecular surgery
5 pages, 3 figures, 2 tables.-- Issue title: "EMRS 2006 Symposium A: Current Trends in Nanoscience - from Materials to Applications" (Nice, France, May 29-Jun 2, 2006)
Nanoparticles can be made to respond resonantly to a time-varying electromagnetic field with advantageous results related to the transfer of energy from the exciting field to the nanoparticles. The surface of each particle can be heated up, this heat being transmitted into the immediately surrounding tissue. This enables their use as hyperthermia agents delivering toxic amounts of thermal energy to targeted bodies such as tumours. Heating of nanoparticles in a magnetic field is mainly due to inductive coupling (via eddy currents), and in the case of magnetic particles, loss processes during the reorientation of the magnetization (hysteresis losses) or frictional losses (relaxational losses) if the particle can rotate in an environment of sufficiently low viscosity. We use this method to apply heat locally and remotely, dissolving toxic protein deposits of Aβ1–42 (amyloid deposits) via the combined use of weak microwave fields and gold nanoparticles (AuNP) without any bulk heating. This method can be extended to a number of systems where it may be desirable to remove proteins and other aggregates involved in different pathologies
2009-07-30T11:26:50Z
2009-07-30T11:26:50Z
2007-09
artículo
Materials Science and Engineering C 27(5-8): 1236-1240 (2007)
0928-4931
http://hdl.handle.net/10261/15537
10.1016/j.msec.2006.08.003
http://dx.doi.org/10.13039/501100002809
http://dx.doi.org/10.13039/501100005853
eng
https://doi.org/10.1016/j.msec.2006.08.003
closedAccess
Elsevier
oai:digital.csic.es:10261/156122016-05-30T12:43:41Zcom_10261_46com_10261_3com_10261_10252col_10261_299col_10261_10253
2009-08-03T11:21:45Z
urn:hdl:10261/15612
From nanosnakes to nanosheets: a matrix-mediated shape evolution
Muñoz Rojas, David
Oró, Judith
Gómez-Romero, P.
Consejo Superior de Investigaciones Científicas (España)
European Commission
Ministerio de Ciencia e Innovación (España)
Ministerio de Ciencia e Innovación (España)
Consejo Superior de Investigaciones Científicas (España)
European Commission
Ag@PPy
Nanosnakes
Nanosheets
The remarkable shape transformation of Ag@PPy nanosnakes into Ag@PPy irregular nanosheets is presented. The tortuous nanosnakes are capable of bending and folding under hydrothermal conditions while retaining the crystallographic coherence of their silver core, thus allowing different nanosnake stretches to join according to an oriented attachment mechanism and yielding bigger thin irregular nanosheets. We propose a matrix-mediated nanomaleability mechanism to account for the shape transformation presented here. We think this novel mechanism can also be behind other reported nanostructures shape transformations which are not fully understood yet
2009-08-03T11:21:45Z
2009-08-03T11:21:45Z
2008-12-03
artículo
Journal of Physical Chemistry C 112(51): 20312–20318 (2008)
1932-7447
http://hdl.handle.net/10261/15612
10.1021/jp808187w
http://dx.doi.org/10.13039/501100003339
http://dx.doi.org/10.13039/501100000780
http://dx.doi.org/10.13039/501100004837
eng
http://dx.doi.org/10.1021/jp808187w
Sí
closedAccess
American Chemical Society
oai:digital.csic.es:10261/156152019-02-13T10:40:41Zcom_10261_46com_10261_3com_10261_10252col_10261_299col_10261_10253
2009-08-03T11:39:11Z
urn:hdl:10261/15615
Facile one-pot synthesis of self-assembled silver@polypyrrole core/shell nanosnakes
Gómez-Romero, P.
Ayyad, Omar
Oró, Judith
Muñoz Rojas, David
Consejo Superior de Investigaciones Científicas (España)
European Commission
Saudi Committee for the Relief of Palestinian People
Ministry of Higher Education (Palestinian National Authority)
Core/shell materials
Hybrid materials
Nanostructures
Self-assembly
Silver
Snakes on a plane TEM grid! Tortuous core/shell nanostructures are produced by a simple, additive-free, one-pot hydrothermal reaction at 120-150 °C. Electron diffraction and high-resolution transmission electron microscopy indicate that the inner silver core is coherent. The nanosnakes (see image) form through self-assembly of reduced silver particles inside a polypyrrole matrix.
2009-08-03T11:39:11Z
2009-08-03T11:39:11Z
2008-08-19
artículo
Small 4(9): 1301-1306 (2008)
1613-6810
http://hdl.handle.net/10261/15615
10.1002/smll.200701199
1613-6829
http://dx.doi.org/10.13039/501100003339
http://dx.doi.org/10.13039/501100000780
eng
http://dx.doi.org/10.1002/smll.200701199
closedAccess
John Wiley & Sons
oai:digital.csic.es:10261/156182016-05-30T12:43:44Zcom_10261_10252com_10261_3com_10261_46col_10261_10253col_10261_299
2009-08-03T11:54:31Z
urn:hdl:10261/15618
High-yield preparation of titanium dioxide nanostructures by hydrothermal conditions
Vasquez, Juan
Lira-Cantú, Mónica
Gómez-Romero, P.
Santa Ana, María Angélica
Benavente, Eglantina
González, Guillermo
TiO2-Based nanostructures
Hydrothermal treatment
Neutral surfactant
The effect of the neutral surfactant dodecylamine and octadecylamine on the synthesis of TiO2-based nanostructures by the treatment of anatase with NaOH under hydrothermal conditions in the temperature range 120-150 °C and different reaction times was investigated. The products analyzed by electron microscopy, X-ray diffraction, FT-IR and elemental analysis contains—depending of the amine, the temperature and the duration of the hydrothermal treatment—spherical and tubular species containing the acid H2Ti3O7. The formation of morphologically almost pure phases constituted by nanospheres and nanotubes were obtained at 130 °C after about 30 and 50 h respectively. Using dodecylamine, structurally fragile tubular amine containing nanocomposites are obtained, while in the case of the octadecylamine, notoriously stable purely inorganic nanotubes are formed. The role of the amine in these reactions is discussed.
2009-08-03T11:54:31Z
2009-08-03T11:54:31Z
2009-02
artículo
Journal of Nanoscience and Nanotechnology 9(2): 1103-1107 (2009)
1533-4880
http://hdl.handle.net/10261/15618
10.1166/jnn.2009.C097
eng
http://dx.doi.org/10.1166/jnn.2009.C097
Sí
closedAccess
American Scientific Publishers
oai:digital.csic.es:10261/156712016-05-30T12:43:44Zcom_10261_46com_10261_3com_10261_10252col_10261_299col_10261_10253
2009-08-05T07:03:22Z
urn:hdl:10261/15671
From silver nanoparticles to nanostructures through matrix chemistry
Ayyad, Omar
Muñoz Rojas, David
Oró, Judith
Gómez-Romero, P.
Ministerio de Ciencia e Innovación (España)
Consejo Superior de Investigaciones Científicas (España)
European Commission
Ministry of Higher Education (Palestinian National Authority)
Saudi Committee for the Relief of Palestinian People
Al-Quds University
Agar gel
Silver nanoparticles
Hybrid nanostructures
9 páginas, 5 figuras.
Direct in situ reduction of silver ions by a biopolymer such as agar, without any other reducing nor capping agent is shown in this article to lead either to nanoparticles (typically 12(2) nm in an optimized case) or to more complex nanostructures depending on the reaction conditions used. This approach takes advantage of the porous polymer lattice acting as a template and leads to hybrid Ag–Agar materials with long-term synergic stability. Silver acts as an antibacterial agent for agar whereas the biopolymer prevents agglomeration of the inorganic nanoparticles leading to a stable nanocomposite formed by a thermoreversible biopolymer from which silver nanoparticles can eventually be recovered.
2009-08-05T07:03:22Z
2009-08-05T07:03:22Z
2010
artículo
Journal of Nanoparticle Research 12(1): 337-345 (2010)
1388-0764
http://hdl.handle.net/10261/15671
10.1007/s11051-009-9620-3
1572-896X
http://dx.doi.org/10.13039/501100004837
http://dx.doi.org/10.13039/501100003339
http://dx.doi.org/10.13039/501100000780
eng
http://dx.doi.org/10.1007/s11051-009-9620-3
Sí
closedAccess
Springer
oai:digital.csic.es:10261/190812017-01-27T12:19:50Zcom_10261_31com_10261_3com_10261_10252col_10261_284col_10261_10253
2009-11-27T08:56:37Z
urn:hdl:10261/19081
Single-molecule magnet behaviour in metal–organic nanospheres generated by simple precipitation of Mn12O12 clusters
Imaz, Inhar
Luis, Fernando
Carbonera, Chiara
Ruiz Molina, Daniel
Maspoch, Daniel
European Commission
Ministerio de Ciencia y Tecnología (España)
Diputación General de Aragón
Metal-organic sub-50 nm spherical particles that exhibit single-molecule magnet behaviour have been fabricated by direct precipitation of Mn12O12 clusters in a mixture of acetonitrile and toluene.
2009-11-27T08:56:37Z
2009-11-27T08:56:37Z
2008
artículo
Chemical Communications 10: 1202-1204 (2008)
1359-7345
http://hdl.handle.net/10261/19081
10.1039/B716071B
http://dx.doi.org/10.13039/501100000780
http://dx.doi.org/10.13039/501100006280
eng
closedAccess
Royal Society of Chemistry (UK)
oai:digital.csic.es:10261/191272021-10-27T07:42:30Zcom_10261_31com_10261_3com_10261_46com_10261_10252col_10261_284col_10261_299col_10261_10253
2009-11-30T08:59:07Z
urn:hdl:10261/19127
A hexacarboxylic open-shell building block: synthesis, structure and magnetism of a three-dimensional metal-radical framework
Roques, Nans
Maspoch, Daniel
Luis, Fernando
Camón, Agustín
Wurst, Klaus
Datcu, Angela
Rovira, Concepció
Ruiz Molina, Daniel
Veciana, Jaume
Ministerio de Educación y Ciencia (España)
European Commission
Ministerio de Ciencia y Tecnología (España)
An octahedral hexacarboxylic polychlorotriphenylmethyl radical (PTMHC) and its hydrogenated precursor (aH-PTMHC) have been reacted with Cu(II) and 4,4'-bipyridine to prepare two isomorphic three-dimensional (3-D) coordination polymers of formula [Cu6(PTMHC)2(4,4'-bipy)3(H20)12]n(1) and [Cu6(aH-PTMHC)2(4,4'-bipy)3(EtOH)6(H20)6]n (2). Both 3-D structures can be described as two interpenetrating primitive cubic nets connected through bipyridine linkers, which defines an unusual topology with Schläfi symbol of (62·81)·(66·89). Magnetic properties of both metal-organic frameworks have been studied in detail. 2 shows weak antiferromagnetic interactions between Cu(II) ions at low temperature. In contrast, 1 reveals unexpected metal-radical ferromagnetic interactions (θ=2.1 (2) K). Information on the existence of magnetic ordering and the nature of the ordered phase for 1 has been investigated via very low temperature magnetic susceptibility measurements. Surprisingly, the experimental data indicate the occurrence of 3-D antiferromagnetic ordering below 0.5 K. This latter phenomenon has been explained with specific heat measurements. Experimental results reveal the coexistence of relatively strong ferromagnetic interactions with weaker antiferromagnetic ones, mediated through the bipyridine linkers, which finally determine the low temperature magnetic structure. A deeper study of the data allows the analysis of the magnetic behavior of 1 as a 3-D antiferromagnet, with Tc = 0.39 K, with ferromagnetic exchange interactions that do not propagate with equal strength along the three crystallographic directions above this temperature.
2009-11-30T08:59:07Z
2009-11-30T08:59:07Z
2008
artículo
Journal of Material Chemistry 18(1): 98-108 (2008)
0959-9428
http://hdl.handle.net/10261/19127
10.1039/b713705b
1364-5501
http://dx.doi.org/10.13039/501100000780
http://dx.doi.org/10.13039/501100006280
eng
http://dx.doi.org/10.1039/b713705b
Sí
closedAccess
Royal Society of Chemistry (UK)
oai:digital.csic.es:10261/218782023-01-27T07:53:29Zcom_10261_10252com_10261_3col_10261_10253
2010-03-03T12:07:14Z
urn:hdl:10261/21878
Longitudinal detection of ferromagnetic resonance using x-ray transmission measurements
Boero, G.
Rusponi, S.
Kavich, Jerald
Lodi Rizzini, A.
Piamonteze, Cinthia
Nolting, F.
Tieg, C.
Thiele, J. U.
Gambardella, Pietro
European Research Council
Ministerio de Ciencia e Innovación (España)
11 pages, 6 figures, 1 table, 1 appendix.
We describe a setup for the x-ray detection of ferromagnetic resonance in the longitudinal geometry using element-specific transmission measurements. Thin magnetic film samples are placed in a static magnetic field collinear with the propagation direction of a polarized soft x-ray beam and driven to ferromagnetic resonance by a continuous wave microwave magnetic field perpendicular to it. The transmitted photon flux is measured both as a function of the x-ray photon energy and as a function of the applied static magnetic field. We report experiments performed on a 15 nm film of doped Permalloy (Ni73Fe18Gd7Co2) at the L3/L2-edges of Fe, Co, and Ni. The achieved ferromagnetic resonance sensitivity is about 0.1 monolayers/ (raiz cuadrada de Hz). The obtained results are interpreted in the framework of a conductivity tensor based formalism. The factors limiting the sensitivity as well as different approaches for the x-ray detection of ferromagnetic resonance are discussed.
2010-03-03T12:07:14Z
2010-03-03T12:07:14Z
2009-12-03
artículo
Review of Scientific Instruments Beta 80(12): 123902 (2009)
0034-6748
http://hdl.handle.net/10261/21878
10.1063/1.3267192
http://dx.doi.org/10.13039/501100000781
http://dx.doi.org/10.13039/501100004837
eng
http://dx.doi.org/10.1063/1.3267192
openAccess
American Institute of Physics
oai:digital.csic.es:10261/219522017-02-23T11:17:46Zcom_10261_46com_10261_3com_10261_10252col_10261_299col_10261_10253
2010-03-04T14:15:10Z
urn:hdl:10261/21952
Electrical conductivity and oxygen exchange kinetics of La2NiO4+ thin films grown by chemical vapor deposition
García, Gemma
Burriel, Mónica
Bonanos, Nikolaos
Santiso, José
Chemical exchanges
Chemical vapour deposition
Electrical conductivity
Epitaxial layers
5 pages.-- PACS: 81.15.Aa; 81.15.Gh; 82.33.Ya;
82.20.-w; 82.30.Hk
Epitaxial c-axis oriented La2NiO4+ films were deposited onto SrTiO3 and NdGaO3 substrates by the pulsed injection metal organic chemical vapor deposition technique. Experimental conditions were optimized in order to accurately control the composition, thickness, and texture of the layers. X-ray diffraction was used to confirm the high crystalline quality of the obtained material. Electrical characterizations were performed on thin (50 nm) and thick (335 nm) layers. The total specific conductivity, which is predominantly electronic, was found to be larger for the thinner films measured (50 nm), probably due to the effect of the strain present in the layers. Those thin films (50 nm) showed values even larger than those observed for single crystals and, to our knowledge, are the largest conductivity values reported to date for the La2NiO4+ material. The oxygen exchange kinetics was studied by the electrical conductivity relaxation technique, from which the surface exchange coefficient was determined.
2010-03-04T14:15:10Z
2010-03-04T14:15:10Z
2008-01-15
artículo
Journal of the electrochemical society 155(3): P28-P32 (2008)
0013-4651
http://hdl.handle.net/10261/21952
10.1149/1.2829900
eng
http://dx.doi.org/10.1149/1.2829900
closedAccess
Electrochemical Society
oai:digital.csic.es:10261/279842020-03-12T09:59:17Zcom_10261_36com_10261_4com_10261_10252com_10261_3com_10261_28col_10261_289col_10261_10253col_10261_281
2010-09-23T13:10:56Z
urn:hdl:10261/27984
Scalable fabrication of immunosensors based on carbon nanotube polymer composites
Mendoza Gómez, Ernest
Orozco, Jahir
Jiménez-Jorquera, Cecilia
González-Guerrero, Ana Belén
Calle Martín, Ana
Lechuga, Laura M.
Fernández Sánchez, César
Ministerio de Educación y Ciencia (España)
Consejo Superior de Investigaciones Científicas (España)
European Commission
Ministerio de Educación y Ciencia (España)
Consejo Superior de Investigaciones Científicas (España)
European Commission
7 páginas, 4 figuras.
In this work we present the fabrication and characterization of immunosensors based on polystyrene (PS)–multiwalled carbon nanotube (MWCNT) composites. The electrochemical properties of the sensors have been investigated and show that the surface area is increased upon addition of the MWCNT–PS layer. Furthermore, a plasma activation process is used to partially remove the PS and expose the MWCNTs. This results in a huge increase in the electrochemical area and opens up the possibility of binding biomolecules to the MWCNT wall. The MWCNTs have been functionalized covalently with a model antibody (rabbit IgG). The biosensors have been tested using amperometric techniques and show detection limits comparable to standard techniques such as ELISA.
2010-09-23T13:10:56Z
2010-09-23T13:10:56Z
2008-01-29
artículo
Applied Physics Letters 19(7): 075102 (2008)
0003-6951
http://hdl.handle.net/10261/27984
10.1088/0957-4484/19/7/075102
http://dx.doi.org/10.13039/501100003339
http://dx.doi.org/10.13039/501100000780
eng
http://dx.doi.org/10.1088/0957-4484/19/7/075102
openAccess
American Institute of Physics
oai:digital.csic.es:10261/279972020-03-12T09:59:18Zcom_10261_10252com_10261_3com_10261_28com_10261_4col_10261_10253col_10261_281
2010-09-24T08:45:40Z
urn:hdl:10261/27997
Silicon Photonic Biosensors for Lab-on-a-Chip Applications
Zinoviev, Kirill
Carrascosa, Laura G.
Sánchez del Río, José
Sepúlveda, Borja
Domínguez, Carlos
Lechuga, Laura M.
Ministerio de Educación y Ciencia (España)
Fundación Botín
6 páginas, 8 figuras.
In the last two decades, we have witnessed a remarkable progress in the development of biosensor devices and their application in areas such as environmental monitoring, biotechnology, medical diagnostics, drug screening, food safety, and security, among others. The technology of optical biosensors has reached a high degree of maturity and several commercial products are on the market. But problems of stability, sensitivity, and size have prevented the general use of optical biosensors for real field applications. Integrated photonic biosensors based on silicon technology could solve such drawbacks, offering early diagnostic tools with better sensitivity, specificity, and reliability, which could improve the effectiveness of in-vivo and in-vitro diagnostics. Our last developments in silicon photonic biosensors will be showed, mainly related to the development of portable and highly sensitive integrated photonic sensing platforms.
2010-09-24T08:45:40Z
2010-09-24T08:45:40Z
2008
artículo
Advances in Optical Technologies 2008: 383927 (2008)
1687-6393
http://hdl.handle.net/10261/27997
10.1155/2008/383927
http://dx.doi.org/10.13039/501100006373
eng
http://dx.doi.org/10.1155/2008/383927
openAccess
Hindawi Publishing Corporation
oai:digital.csic.es:10261/279982020-03-12T09:59:16Zcom_10261_10252com_10261_3col_10261_10253
2010-09-24T09:29:01Z
urn:hdl:10261/27998
La revolución de la Nanomedicina
Lechuga, Laura M.
6 páginas, 4 figuras.
Uno de los grandes retos a los que se enfrenta
la medicina este siglo es el desarrollo de técnicas de
diagnóstico precoz para numerosas enfermedades
así como el desarrollo de técnicas de regeneración de
órganos y tejidos dañados dentro de nuestro cuerpo.
Encontrar una adecuada solución a estos retos podría
tener una gran repercusión en la calidad de vida de
nuestra sociedad en un futuro cercano. La emergencia
de una nueva disciplina, denominada Nanomedicina,
promete alcanzar estos ambiciosos objetivos.
2010-09-24T09:29:01Z
2010-09-24T09:29:01Z
2008
artículo
Revista SEDISA 10: 38-43 (2008)
http://hdl.handle.net/10261/27998
spa
openAccess
Sociedad Española de Directivos de la Salud
oai:digital.csic.es:10261/280022020-03-12T09:59:16Zcom_10261_10252com_10261_3col_10261_10253
2010-09-24T13:28:16Z
urn:hdl:10261/28002
Microcantilever-based platforms as biosensing tools
Álvarez, Mar
Lechuga, Laura M.
Fundación Botín
10 páginas, 7 figuras, 1 tabla.
The fast and progressive growth of the biotechnology and pharmaceutical fields forces the development of new and powerful sensing techniques for process optimization and detection of biomolecules at very low concentrations. During the last years, the simplest MEMS structures, i.e. microcantilevers, have become an emerging and promising technology for biosensing applications, due to their small size, fast response, high sensitivity and their compatible integration into lab-on-a-chip devices. This article provides an overview of some of the most interesting bio-detections carried out during the last 2–3 years with the microcantilever-based platforms, which highlight the continuous expansion of this kind of sensor in the medical diagnosis field, reaching limits of detection at the single molecule level.
2010-09-24T13:28:16Z
2010-09-24T13:28:16Z
2010
artículo
Analyst 135: 827-836 (2010)
0003-2654
http://hdl.handle.net/10261/28002
10.1039/b908503n
http://dx.doi.org/10.13039/501100006373
eng
http://dx.doi.org/10.1039/b908503n
closedAccess
Royal Society of Chemistry (UK)
oai:digital.csic.es:10261/280102020-03-12T09:59:16Zcom_10261_10252com_10261_3com_10261_89col_10261_10253col_10261_342
2010-09-27T11:56:34Z
urn:hdl:10261/28010
Influence of the linker type on the Au–S binding properties of thiol and disulfide-modified DNA self-assembly on polycrystalline gold
Martínez-Orellana, Lidia
Carrascosa, Laura G.
Huttel, Yves
Lechuga, Laura M.
Román García, Elisa Leonor
Ministerio de Ciencia e Innovación (España)
8 páginas, 5 figuras.
We investigate the Au–S binding properties of thiol and disulfide-modified DNA on polycrystalline gold by means of X-ray photoelectron spectroscopy in conditions close to dynamic processes of biosensors. The dependence of the immobilisation period on the quality and density of the self-assembly process of thiol (SH–(CH2)6–DNA), disulfide (DNA–CH2)6–SS–(CH2)6–DNA and DMTO–SS–(CH2)6–DNA) sulfur-modified oligonucleotide solutions (1 μM) that are employed for bioreceptor immobilisation is analysed. Two electronic components are found in the analysis of the S 2p core levels. One of them is clearly associated to thiolate formation, while the other can be associated to different origins. In order to identify the origin of this last component, a quantification of the non-specifically adsorbed species has been performed by rinsing the self-assembled monolayers (SAMs) with a mercapto hexanol (MCH) solution. It has been found that non-specifically adsorbed species contribute only partially to the appearance of this sulfur peak component in SAMs formed from disulfides. Electron bombardment was performed to study the evolution of this component as a consequence of surface degradation due to radiation effects. The results are also correlated with the possible presence of disulfides. We found that MCH is not stable during the measurements. The evolution of this compound and the possible causes for this behaviour are discussed.
2010-09-27T11:56:34Z
2010-09-27T11:56:34Z
2010-04-07
artículo
Physical Chemistry Chemical Physics 12(13): 3301-3308 (2010)
1463-9076
http://hdl.handle.net/10261/28010
10.1039/B924504A
http://dx.doi.org/10.13039/501100004837
eng
http://dx.doi.org/10.1039/B924504A
closedAccess
Royal Society of Chemistry (UK)
oai:digital.csic.es:10261/280012020-03-12T09:59:18Zcom_10261_10252com_10261_3col_10261_10253
2010-09-24T13:14:29Z
urn:hdl:10261/28001
Surface plasmon resonance biosensors for highly sensitive detection in real samples
Sepúlveda, Borja
Carrascosa, Laura G.
Regatos, David
Otte, Marinus A.
Fariña, David
Lechuga, Laura M.
Fundación Botín
Surface plasmon resonance
DNA detection
Protein biosensing
Magneto-optic SPR
Localized surface plasmon resonance
11 páginas, 9 figuras.-- Trabajo presentado en la conferencia "Biosensing II", 4-Agosto-2009,
San Diego, CA, USA; Editores: Manijeh Razeghi, Hooman Mohseni.
In this work we summarize the main results obtained with the portable surface plasmon resonance (SPR) device developed in our group (commercialised by SENSIA, SL, Spain), highlighting its applicability for the real-time detection of extremely low concentrations of toxic pesticides in environmental water samples. In addition, we show applications in clinical diagnosis as, on the one hand, the real-time and label-free detection of DNA hybridization and single point mutations at the gene BRCA-1, related to the predisposition in women to develop an inherited breast cancer and, on the other hand, the analysis of protein biomarkers in biological samples (urine, serum) for early detection of diseases. Despite the large number of applications already proven, the SPR technology has two main drawbacks: (i) not enough sensitivity for some specific applications (where pM-fM or single-molecule detection are needed) (ii) low multiplexing capabilities. In order solve such drawbacks, we work in several alternative configurations as the Magneto-optical Surface Plasmon Resonance sensor (MOSPR) based on a combination of magnetooptical and ferromagnetic materials, to improve the SPR sensitivity, or the Localized Surface Plasmon Resonance (LSPR) based on nanostructures (nanoparticles, nanoholes,...), for higher multiplexing capabilities.
2010-09-24T13:14:29Z
2010-09-24T13:14:29Z
2009-08-20
artículo
Proceedings of SPIE 7397: 7397OY (2009)
0277-786X
http://hdl.handle.net/10261/28001
10.1117/12.827062
http://dx.doi.org/10.13039/501100006373
eng
http://dx.doi.org/10.1117/12.827062
openAccess
The International Society for Optics and Photonics
oai:digital.csic.es:10261/279992020-03-12T09:59:15Zcom_10261_28com_10261_4com_10261_10252com_10261_3col_10261_281col_10261_10253
2010-09-24T12:14:21Z
urn:hdl:10261/27999
Biosensing microsystem platforms based on the integration of Si Mach-Zehnder interferometer, microfluidics and grating couplers
Lechuga, Laura M.
Zinoviev, Kirill
Fernández, L.
Elizalde, J.
Hidalgo Alonso, Orlando E.
Domínguez, Carlos
Ministerio de Educación y Ciencia (España)
Fundación Botín
Photonic biosensor
Mach-Zender
Interferometer
Microfluidics
Lab-on-a-chip
8 páginas, 7 figuras.-- Trabajo presentado en la conferencia "Silicon Photonics IV", 26-Enero-2009, San Jose, CA, USA; Editores: Joel A. Kubby, Graham T. Reed.
We have achieved the design, fabrication and packaging of microfluidic networks with photonic sensors for novel labon- chip platforms which incorporate the on-chip biosensing detection. As sensors, we used an integrated Mach-Zehnder interferometer (MZI) based on TIR waveguides (Si/SiO2/Si3N4) of micro/nanodimensions for evanescent field detection of biomolecular interactions onto the sensing areas. For the lab-on-a-chip development, the biosensors have been integrated with a 3D microfluidic polymer network. In addition, we have developed a novel hybrid device for coupling light into the waveguides of the Mach-Zehnder sensor. The coupling hybrid device is composed of a thin film of diffraction gratings fixed to a polydimethylsiloxane film. The optical characterization has shown the excellent compatibility and integration between fabrication technologies of silicon MZI, SU-8 polymer microfluidic network and mountable grating couplers.
2010-09-24T12:14:21Z
2010-09-24T12:14:21Z
2009-02-17
artículo
Proceedings of SPIE 7220: 72200L (2009)
0277-786X
http://hdl.handle.net/10261/27999
10.1117/12.809166
http://dx.doi.org/10.13039/501100006373
eng
http://dx.doi.org/10.1117/12.809166
openAccess
The International Society for Optics and Photonics
oai:digital.csic.es:10261/280882021-06-14T08:05:44Zcom_10261_10252com_10261_3com_10261_36com_10261_4col_10261_10253col_10261_289
2010-09-30T08:31:43Z
urn:hdl:10261/28088
Plasmon-Induced Magneto-Optical Activity in Nanosized Gold Disks
Sepúlveda, Borja
González-Díaz, Juan B.
García-Martín, Antonio
Lechuga, Laura M.
Armelles Reig, Gaspar
European Commission
Ministerio de Ciencia e Innovación (España)
European Commission
Comunidad de Madrid
Fundación Botín
Ministerio de Ciencia e Innovación (España)
Consejo Superior de Investigaciones Científicas (España)
4 páginas, 3 figuras.-- PACS numbers: 78.67.Bf, 73.20.Mf, 78.20.Ls, 78.68.+m
In this Letter we show that nanostructures made out of pure noble metals can exhibit measurable
magneto-optic activity at low magnetic fields. This phenomenon occurs when the localized surface
plasmon resonance of the nanostructure is excited in the presence of a static magnetic field parallel to the
propagation of incident light. The large magneto-optical response observed comes from an increase of the
magnetic Lorentz force induced by the large collective movement of the conduction electrons in the
nanostructures when the resonance is excited.
2010-09-30T08:31:43Z
2010-09-30T08:31:43Z
2010-04-07
artículo
Physical Review Letters 104(14): 147401 (2010)
0031-9007
http://hdl.handle.net/10261/28088
10.1103/PhysRevLett.104.147401
http://dx.doi.org/10.13039/501100000780
http://dx.doi.org/10.13039/501100003339
http://dx.doi.org/10.13039/501100004837
http://dx.doi.org/10.13039/100012818
http://dx.doi.org/10.13039/501100006373
eng
Publisher's version
http://dx.doi.org/10.1103/PhysRevLett.104.147401
info:eu-repo/grantAgreement/EC/FP7/214107
openAccess
American Physical Society
oai:digital.csic.es:10261/280892020-03-12T09:59:15Zcom_10261_36com_10261_4com_10261_10252com_10261_3col_10261_289col_10261_10253
2010-09-30T08:46:27Z
urn:hdl:10261/28089
Au/Fe/Au multilayer transducers for magneto-optic surface plasmon resonance sensing
Regatos, David
Fariña, David
Calle Martín, Ana
Cebollada, Alfonso
Sepúlveda, Borja
Armelles Reig, Gaspar
Lechuga, Laura M.
Ministerio de Ciencia e Innovación (España)
Comunidad de Madrid
Ministerio de Ciencia e Innovación (España)
Fundación Botín
Eusko Jaurlaritza
European Commission
6 páginas, 5 figuras.
In this paper, we analyze the magnetoplasmonic (MP) features and sensing capabilities of Au/Fe/Au trilayer structures, as transducers of the magneto-optic surface plasmon resonance (MOSPR) biosensor. This biosensor, which can surpass the sensitivity of the standard SPR sensor, is based on a MP modulation technique generated by the simultaneous stimulation of the surface plasmon polaritons (SPP) and the transversal magneto-optical Kerr effect (TMOKE). We study the magneto-optical activity of the trilayers as a function of the thickness and position of the Fe layer. We first demonstrate that this kind of structure allows modulating the SPP through an external magnetic field and moreover, induce a strong enhancement of the TMOKE effect. The modulation of the SPP is linearly proportional to the thickness of Fe layer and inversely proportional to the distance between the Fe layer and the external dielectric medium. Finally, we experimentally confirm a twofold increase in the MOSPR sensitivity with respect to the intensity-interrogated SPR biosensor in bulk refractive-index changes, keeping a similar chemical resistance and stability, unprecedented in other MP transducers, and biofunctionalization protocols.
2010-09-30T08:46:27Z
2010-09-30T08:46:27Z
2010-09
artículo
Physical Review Letters 108(5): 054502 (2010)
0031-9007
http://hdl.handle.net/10261/28089
10.1063/1.3475711
http://dx.doi.org/10.13039/501100006373
http://dx.doi.org/10.13039/501100004837
http://dx.doi.org/10.13039/501100003086
http://dx.doi.org/10.13039/100012818
http://dx.doi.org/10.13039/501100000780
eng
http://dx.doi.org/10.1063/1.3475711
S2009/TIC-1476/MICROSERES
openAccess
American Physical Society
oai:digital.csic.es:10261/282842020-03-12T09:59:15Zcom_10261_28com_10261_4com_10261_10252com_10261_3col_10261_281col_10261_10253
2010-10-07T10:44:02Z
urn:hdl:10261/28284
Biosensing microsystems: fast, label-free, real-time clinical testing
Lechuga, Laura M.
Zinoviev, Kirill
Hidalgo Alonso, Orlando E.
Domínguez, Carlos
Elizalde, J.
2 páginas, 2 figuras.-- Biomedical Optics and Medical Imaging.
Integration of highly sensitive photonic biosensors and microfluidic technologies provide new possibilities for molecular diagnostics.
2010-10-07T10:44:02Z
2010-10-07T10:44:02Z
2008-12-03
artículo
SPIE newsroom: 2008.
1818-2259
http://hdl.handle.net/10261/28284
10.1117/2.1200812.1377
eng
http://dx.doi.org/10.1117/2.1200812.1377
openAccess
The International Society for Optics and Photonics
oai:digital.csic.es:10261/290492020-03-12T09:59:16Zcom_10261_10252com_10261_3col_10261_10253
2010-11-12T11:44:27Z
urn:hdl:10261/29049
Identification of the optimal spectral region for plasmonic and nanoplasmonic sensing
Otte, Marinus A.
Sepúlveda, Borja
Ni, Weihai
Pérez-Juste, Jorge
Liz-Marzán, Luis Manuel
Lechuga, Laura M.
Generalitat de Catalunya
European Commission
Fundación Botín
Ministerio de Ciencia e Innovación (España)
Surface plasmon resonance
Localized surface plasmon resonance
Sensing
Biosensing
Sensitivity
Figure of merit
Nanorods
This document is the unedited Author’s version of a Submitted Work that was subsequently accepted for publication in ACS Nano, copyright © American Chemical Society after peer review. To access the final edited and published work see http://pubs.acs.org/articlesonrequest/AOR-jfCkKFwsJwtEYkHTFzG7
We present a theoretical and experimental study involving the sensing characteristics of wavelength interrogated plasmonic sensors based on Surface Plasmon Polaritons (SPP) in planar gold films and on Localized Surface Plasmon Resonances (LSPR) of single gold nanorods. The tunability of both sensing platforms allowed us to analyze their bulk and surface sensing characteristics as a function of the plasmon resonance position. We demonstrate that a general figure of merit (FOM), which is equivalent in wavelength and energy scales, can be employed to mutually compare both sensing schemes. Most interestingly, this FOM has revealed a spectral region for which the surface sensitivity performance of both sensor types is optimized, which we attribute to the intrinsic dielectric properties of plasmonic materials. Additionally, in good agreement with theoretical predictions, we experimentally demonstrate that, although the SPP sensor offers a much better bulk sensitivity, the LSPR sensor shows an approximately 15% better performance for surface sensitivity measurements when its FOM is optimized. However, optimization of the substrate refractive index and the accessibility of the relevant molecules to the nanoparticles can lead to a total 3-fold improvement of the FOM in LSPR sensors.
2010-11-12T11:44:27Z
2010-11-12T11:44:27Z
2009-11-30
artículo
ACS Nano 4 (1): 349-357 (2010)
1936-0851
http://hdl.handle.net/10261/29049
10.1021/nn901024e
1936-086X
http://dx.doi.org/10.13039/501100002809
http://dx.doi.org/10.13039/501100000780
http://dx.doi.org/10.13039/501100006373
http://dx.doi.org/10.13039/501100004837
eng
http://dx.doi.org/10.1021/nn901024e
openAccess
American Chemical Society
oai:digital.csic.es:10261/313662020-03-12T09:59:16Zcom_10261_10252com_10261_3col_10261_10253
2011-01-20T09:34:17Z
urn:hdl:10261/31366
Magneto-optic sensitivity enhancement in plasmonic sensors
Sepúlveda, Borja
Calle Martín, Ana
Lechuga, Laura M.
Armelles Reig, Gaspar
3 páginas.
2011-01-20T09:34:17Z
2011-01-20T09:34:17Z
2008
artículo
Bio World Europe, The Magazine for the Life Science Industry 01: 12-14 (2008)
1802-2685
http://hdl.handle.net/10261/31366
eng
http://www.bioworld-europe.com/portal/index.php?option=com_frontpage&Itemid=113
closedAccess
South Bohemian Agency for Support to Innovative Enterprising
oai:digital.csic.es:10261/313702020-03-12T09:59:15Zcom_10261_28com_10261_4com_10261_10252com_10261_3col_10261_281col_10261_10253
2011-01-20T10:13:37Z
urn:hdl:10261/31370
Discriminating the carboxylic groups from the total acidic sites in oxidized multi-wall carbon nanotubes by means of acid–base titration
González-Guerrero, Ana Belén
Mendoza Gómez, Ernest
Pellicer, Eva
Alzina, Francesc
Fernández Sánchez, César
Lechuga, Laura M.
Ministerio de Educación y Ciencia (España)
4 páginas, 4 figuras.
This work reports on the quantitative determination of the carboxylic groups created upon HNO3 treatment at multi-wall carbon nanotube (MWCNT) surface. To this purpose, MWCNTs have been oxidized by refluxing in acid for different periods of time (from 1 h to 12 h). The main goal of the present study comprises the development of a simple analytical methodology based on Boehm’s titration that enables the rapid estimation of the total carboxylic groups and their discrimination from the total oxidized sites created at MWCNT surface as a result of the acid treatment. The trends observed are correlated with Raman spectroscopy analyses.
2011-01-20T10:13:37Z
2011-01-20T10:13:37Z
2008-09-10
artículo
Chemical Physics Letters 462(4-6): 256-259 (2008)
0009-2614
http://hdl.handle.net/10261/31370
10.1016/j.cplett.2008.07.071
eng
http://dx.doi.org/10.1016/j.cplett.2008.07.071
closedAccess
Elsevier
oai:digital.csic.es:10261/313782021-12-28T16:26:13Zcom_10261_10252com_10261_3col_10261_10253
2011-01-20T10:59:18Z
urn:hdl:10261/31378
Label-Free Pathogen Detection with Sensor Chips Assembled from Peptide Nanotubes
Rica, Roberto de la
Mendoza Gómez, Ernest
Lechuga, Laura M.
Matsui, Hiroshi
Department of Energy (US)
National Science Foundation (US)
National Institutes of Health (US)
Ministerio de Ciencia y Tecnología (España)
European Commission
Consejo Superior de Investigaciones Científicas (España)
Bionanotechnology
Peptide nanotubes
Self-assembly
Sensors
Viruses
4 páginas, 3 figuras.-- Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/anie.200804299.
A robust viral sensor was developed by bridging a pair of gold electrodes with antibody-coated peptide nanotubes. The nanotubes concentrated the target virus on their surface by molecular recognition between the antibody and the virus (see picture). The nanotubes fit perfectly within the electric field line distribution to enable the extremely sensitive impedimetric detection of viral particles.
2011-01-20T10:59:18Z
2011-01-20T10:59:18Z
2008-12-01
artículo
Angewandte Chemie - International Edition 47(50): 9752-9755 (2008)
1433-7851
http://hdl.handle.net/10261/31378
10.1002/anie.200804299
http://dx.doi.org/10.13039/100000001
http://dx.doi.org/10.13039/100000002
http://dx.doi.org/10.13039/501100006280
http://dx.doi.org/10.13039/501100000780
http://dx.doi.org/10.13039/501100003339
http://dx.doi.org/10.13039/100000015
18989870
eng
http://dx.doi.org/10.1002/anie.200804299
closedAccess
Wiley-Blackwell
oai:digital.csic.es:10261/313882020-03-12T09:59:15Zcom_10261_10252com_10261_3col_10261_10253
2011-01-20T11:26:30Z
urn:hdl:10261/31388
Assessment of catalyst particle removal in multi-wall carbon nanotubes by highly sensitive magnetic measurements
Pellicer, Eva
González-Guerrero, Ana Belén
Nogués, Josep
Lechuga, Laura M.
Mendoza Gómez, Ernest
Ministerio de Educación y Ciencia (España)
Comisión Interministerial de Ciencia y Tecnología, CICYT (España)
Generalitat de Catalunya
European Commission
Consejo Superior de Investigaciones Científicas (España)
6 páginas, 4 figuras, 1 tabla.
The purity of the multi-wall carbon nanotubes (MWCNTs) from catalyst nanoparticles (cobalt and iron) after conventional nitric acid refluxing has been assessed by standard methods and magnetic measurements. X-ray diffraction and energy dispersive X-ray spectroscopy analyses are not suitable since the catalyst amounts quickly become beyond the detection limit of such techniques. Inductively coupled plasma spectroscopy is useful for this purpose, however it requires a large amount of sample and a long sample processing time since the MWCNTs must be completely destroyed. By contrast, magnetic measurements are a fast and nondestructive method to monitor the catalyst content, showing the existence of a small but detectable signal even for the purest sample, still far from its detection limit. Hence, magnetic measurements are extremely sensitive to detect catalyst impurities and can be used as a quick, first order, tool to evaluate the level of magnetic impurities.
2011-01-20T11:26:30Z
2011-01-20T11:26:30Z
2009-03
artículo
Carbon 47(3): 758-763 (2009)
0008-6223
http://hdl.handle.net/10261/31388
10.1016/j.carbon.2008.11.007
http://dx.doi.org/10.13039/501100007273
http://dx.doi.org/10.13039/501100002809
http://dx.doi.org/10.13039/501100000780
http://dx.doi.org/10.13039/501100003339
eng
http://dx.doi.org/10.1016/j.carbon.2008.11.007
closedAccess
Elsevier
oai:digital.csic.es:10261/313892020-03-12T09:59:16Zcom_10261_10252com_10261_3com_10261_36com_10261_4col_10261_10253col_10261_289
2011-01-20T11:41:29Z
urn:hdl:10261/31389
Label-free detection of DNA mutations by SPR: application to the early detection of inherited breast cancer
Carrascosa, Laura G.
Calle Martín, Ana
Lechuga, Laura M.
Fundación Botín
SPR biosensor
DNA hybridization
DNA mutation
BRCA-1
Breast cancer
10 páginas, 6 figuras, 2 tablas.
A screening analysis of DNA hybridization and
the presence of DNA mutations using an surface plasmon
resonance (SPR) biosensor is shown. The influence of lateral
and vertical spacers, as well as several hybridization conditions,
was studied to optimize the differentiation between
fully complementary and mismatched DNA strands. Our
results demonstrated that SPR biosensors were able to detect
mismatch sequences related to inherited breast cancer, with
high specificity and sensitivity. Using PCR synthetic sequences
as targets, mutant sequences were clearly discriminated
from fully complementary ones, and detection limits below
50 nM were achieved.
2011-01-20T11:41:29Z
2011-01-20T11:41:29Z
2009
artículo
Analytical and Bioanalytical Chemistry 393(4): 1173-1182 (2009)
1618-2642
http://hdl.handle.net/10261/31389
10.1007/s00216-008-2555-1
http://dx.doi.org/10.13039/501100006373
eng
http://dx.doi.org/10.1007/s00216-008-2555-1
closedAccess
Springer
oai:digital.csic.es:10261/314102021-06-11T11:35:07Zcom_10261_25com_10261_1com_10261_10252com_10261_3com_10261_36com_10261_4col_10261_278col_10261_10253col_10261_289
2011-01-21T09:43:29Z
urn:hdl:10261/31410
Determination of human growth hormone in human serum samples by surface plasmon resonance immunoassay
Treviño, Juan
Calle Martín, Ana
Rodríguez Frade, José Miguel
Mellado, Mario
Lechuga, Laura M.
Fundació La Marató de TV3
Fundación Botín
Pfizer
Consejo Superior de Investigaciones Científicas (España)
SPR
Immunosensor
Self-assembled monolayer
hGH
Point-of-care device
Serum
6 páginas, 4 figuras, 1 tabla.
A surface plasmon resonance immunoassay has been developed to determine human growth hormone (hGH) directly and without pre-treatment in human serum samples. A binding inhibition immunoassay was employed. Antibody concentration, assay buffer and regeneration solution have been optimized in order to reach the best performance and the lower non-specific binding of the matrix components to the sensor surface. The lowest detection limit was 6 ng/mL, with a working range covering the physiological range. Reproducibility of the assay was excellent with both intra-assay and inter-assay relative standard deviations <5%, while a variation of 2.19% was obtained employing different sensor chips. Reutilization of the sensor surface allows its continuous use over 50 measurements with a signal drop <20%. The SPR immunoassay results were validated using enzyme-linked immunosorbent assay (ELISA) showing an excellent correlation (R2 = 0.985). A portable and fully automated system (Sensia SL) was employed in this work. This is the first SPR biosensor assay capable of detecting relevant concentrations of a clinical analyte in serum. This study shows the potentials of this device as a diagnostic tool for the detection of multiple clinical analytes.
2011-01-21T09:43:29Z
2011-01-21T09:43:29Z
2009-05-15
artículo
Talanta 78(3): 1011-1016 (2009)
0039-9140
http://hdl.handle.net/10261/31410
10.1016/j.talanta.2009.01.012
http://dx.doi.org/10.13039/100008666
http://dx.doi.org/10.13039/501100006373
http://dx.doi.org/10.13039/100004319
http://dx.doi.org/10.13039/501100003339
eng
http://dx.doi.org/10.1016/j.talanta.2009.01.012
closedAccess
Elsevier
oai:digital.csic.es:10261/314112020-03-12T09:59:16Zcom_10261_10252com_10261_3col_10261_10253
2011-01-21T09:53:20Z
urn:hdl:10261/31411
LSPR-based nanobiosensors
Sepúlveda, Borja
Angelomé, Paula C.
Lechuga, Laura M.
Liz-Marzán, Luis Manuel
Ministerio de Ciencia e Innovación (España)
Xunta de Galicia
Fundación Botín
Biosensors
Surface plasmons
Metal nanoparticles
8 páginas, 5 figuras.-- Review.
Recent progress in nano-optics has paved the route toward the development of highly sensitive and label-free optical transducers using the localized surface plasmon resonance (LSPR) of metal nanostructures. In this review we describe the basis behind LSPR sensing and summarize the latest progress regarding nanostructure fabrication techniques and biosensing applications. Direct colorimetric assays reaching sensitivities in the zeptomolar range, or miniaturized multiplexed sensors constitute cutting-edge research in the LSPR biosensing field. We finally discuss the challenges that LSPR biosensors should face in order to be used in the near-future as commercial devices.
2011-01-21T09:53:20Z
2011-01-21T09:53:20Z
2009-06
artículo
Nano Today 4(3): 244-251 (2009)
1748-0132
http://hdl.handle.net/10261/31411
10.1016/j.nantod.2009.04.001
http://dx.doi.org/10.13039/501100004837
http://dx.doi.org/10.13039/501100006373
http://dx.doi.org/10.13039/501100010801
eng
http://dx.doi.org/10.1016/j.nantod.2009.04.001
closedAccess
Elsevier
oai:digital.csic.es:10261/314122020-03-12T09:59:17Zcom_10261_10252com_10261_3col_10261_10253
2011-01-21T10:01:10Z
urn:hdl:10261/31412
Sensitivity enhancement of nanoplasmonic sensors in low refractive index substrates
Brian, Björn
Sepúlveda, Borja
Alaverdyan, Yury
Lechuga, Laura M.
Käll, Mikael
Swedish Research Council
Swedish Foundation for Strategic Research
Fundación Botín
9 páginas, 4 figuras, 1 tabla.-- OCIS codes: (130.6010) Sensors; (240.6680) Surface Plasmons; (310.6845) Thin film devices
and applications; (260.3910) Metal optics
Metal films perforated by nanoholes constitute a powerful
platform for surface plasmon resonance biosensing. We find that the
refractive index sensitivity of nanohole arrays increases if their resonance is
red-shifted by increasing the separation distance between holes. However,
an additional sensitivity enhancement occurs if the nanohole sensors are
manufactured on low index substrates, despite the fact such substrates
significantly blue-shift the resonance. We find a ~40% higher bulk
refractive index sensitivity for a system of ~100 nm holes in 20 nm gold
films fabricated on Teflon substrates (n=1.32) compared to the case when
conventional glass substrates (n=1.52) are used. A similar improvement is
observed for the case when a thin layer of dielectric material is deposited on
the samples. These results can be understood by considering the electric
field distribution induced by the so-called antisymmetric surface plasmon
polariton in the thin gold films.
2011-01-21T10:01:10Z
2011-01-21T10:01:10Z
2009
artículo
Optics Express 17(3): 2015-2023 (2009)
1094-4087
http://hdl.handle.net/10261/31412
10.1364/OE.17.002015
http://dx.doi.org/10.13039/501100006373
eng
http://dx.doi.org/10.1364/OE.17.002015
openAccess
Optical Society of America
oai:digital.csic.es:10261/314132021-06-11T11:35:08Zcom_10261_10252com_10261_3com_10261_36com_10261_4com_10261_25com_10261_1col_10261_10253col_10261_289col_10261_278
2011-01-21T10:09:42Z
urn:hdl:10261/31413
Surface plasmon resonance immunoassay analysis of pituitary hormones in urine and serum samples
Treviño, Juan
Calle Martín, Ana
Rodríguez Frade, José Miguel
Mellado, Mario
Lechuga, Laura M.
Fundació La Marató de TV3
Fundación Botín
Consejo Superior de Investigaciones Científicas (España)
Pfizer
SPR
Immunosensor
hTSH
hGH
hFSH
hLH
7 páginas, 5 figuras, 1 tabla.
Background: Direct determination of four pituitary peptide hormones: human thyroid stimulating hormone (hTSH), growth hormone (hGH), follicle stimulating hormone (hFSH), and luteinizing hormone (hLH) has been carried out using a portable surface plasmon resonance (SPR) immunosensor.
Methods: A commercial SPR biosensor was employed. The immobilization of the hormones was optimized and monoclonal antibodies were selected in order to obtain the best sensor performance. Assay parameters as running buffer and regeneration solution composition or antibody concentration were adjusted to achieve a sensitive analyte detection.
Results: The performance of the assays was assessed in buffer solution, serum and urine, showing sensitivity in the range from 1 to 6 ng/mL. The covalent attachment of the hormones ensured the stability of the SPR signal through repeated use in up to 100 consecutive assay cycles. Mean intra- and inter-day coefficients of variation were all < 7%, while batch-assay variability using different sensor surfaces was < 5%.
Conclusions: Taking account both the excellent reutilization performance and the outstanding reproducibility, this SPR immunoassay method turns on a highly reliable tool for endocrine monitoring in laboratory and point-of-care (POC) settings.
2011-01-21T10:09:42Z
2011-01-21T10:09:42Z
2009-05
artículo
Clinica Chimica Acta 403(1-2): 56-62 (2009)
0009-8981
http://hdl.handle.net/10261/31413
10.1016/j.cca.2009.01.015
http://dx.doi.org/10.13039/100008666
http://dx.doi.org/10.13039/501100006373
http://dx.doi.org/10.13039/501100003339
http://dx.doi.org/10.13039/100004319
eng
http://dx.doi.org/10.1016/j.cca.2009.01.015
closedAccess
Elsevier
oai:digital.csic.es:10261/314142021-06-11T11:35:08Zcom_10261_10252com_10261_3com_10261_25com_10261_1com_10261_36com_10261_4col_10261_10253col_10261_278col_10261_289
2011-01-21T10:21:28Z
urn:hdl:10261/31414
Single- and multi-analyte determination of gonadotropic hormones in urine by Surface Plasmon Resonance immunoassay
Treviño, Juan
Calle Martín, Ana
Rodríguez Frade, José Miguel
Mellado, Mario
Lechuga, Laura M.
Fundació La Marató de TV3
Fundación Botín
Consejo Superior de Investigaciones Científicas (España)
Pfizer
SPR
Immunosensor
Self-assembled monolayer
Human follicle stimulating hormone
Human luteinizing hormone
Point-of-care device
Urine samples
8 páginas, 3 figuras, 4 tablas.
Single- and multi-analyte detection of two gonadotropic hormones (follicle stimulating hormone (hFSH) and luteinizing hormone (hLH)) was achieved by a Surface Plasmon Resonance (SPR) immunoassay on untreated human urine samples. Multi-analyte detection was accomplished using two alternative formats which are based in the individual or simultaneous immobilization of the hormones on the sensor surface. The lowest detection limit for both hormones in urine was found to be 1 ng mL−1, which in international units (IU) in terms of the World Health Organization (WHO) standards represents 8 mIU mL−1 of hLH and 14 mIU mL−1 of hFSH, respectively. The reliability of the assay was demonstrated by intra- and inter-assay variabilities <6%, chip-to-chip variabilities <5%, recoveries in the range of 80–120% and stability of the sensor response through more than 100 measurements. The sensitivity of this biosensing methodology renders it in a useful technique for the diagnosis of reproductive disorders, as well as for fertility monitoring.
2011-01-21T10:21:28Z
2011-01-21T10:21:28Z
2009-08-11
artículo
Analytica Chimica Acta 647(2): 202-209 (2009)
0003-2670
http://hdl.handle.net/10261/31414
10.1016/j.aca.2009.06.002
http://dx.doi.org/10.13039/100008666
http://dx.doi.org/10.13039/501100006373
http://dx.doi.org/10.13039/501100003339
http://dx.doi.org/10.13039/100004319
eng
http://dx.doi.org/10.1016/j.aca.2009.06.002
closedAccess
Elsevier
oai:digital.csic.es:10261/314152020-03-12T09:59:17Zcom_10261_28com_10261_4com_10261_10252com_10261_3col_10261_281col_10261_10253
2011-01-21T10:37:01Z
urn:hdl:10261/31415
Plasma-activated multi-walled carbon nanotube–polystyrene composite substrates for biosensing
Fernández Sánchez, César
Pellicer, Eva
Orozco, Jahir
Jiménez-Jorquera, Cecilia
Lechuga, Laura M.
Mendoza Gómez, Ernest
Ministerio de Ciencia e Innovación (España)
Ministerio de Educación y Ciencia (España)
Consejo Superior de Investigaciones Científicas (España)
European Commission
7 páginas, 6 figuras, 2 tablas.-- PACS 87.80.-y Biophysical techniques (research methods)
52.77.Bn Etching and cleaning
85.35.Kt Nanotube devices
07.07.Mp Transducers
79.60.-i Photoemission and photoelectron spectra.
Carbon nanotube–polymer composites have shown to be suitable materials for the fabrication of
electrochemical transducers. The exposed surface of these materials is commonly passivated by
a very thin layer of the polymer component that buries the conductive carbon particles. Working
with multi-walled carbon nanotube–polystyrene (MWCNT–PS) composite structures, it was
previously described how a simple low power oxygen plasma process produced an effective
etching of the composite surface, thereby exposing the conductive surface of CNTs. This work
shows how this plasma process not only gave rise to a suitable composite conductive surface for
electrochemical sensing but simultaneously exposed and created a high density of
oxygen-containing functional groups at both the CNT and the PS components, without affecting
the material’s mechanical stability. These chemical groups could be effectively modified for the
stable immobilization of biological receptors. A detailed chemical characterization of the
plasma-activated composite surface was possible using x-ray photoelectron spectroscopy. The
material reactivity towards the tethering of a protein was studied and protein–protein
interactions were then evaluated on the modified composite transducers by scanning electron
microscopy. Finally, an amperometric immunosensor approach for the detection of rabbit
Immunoglobulin G target analyte was described and a minimum concentration of 3 ng ml−1
was easily measured.
2011-01-21T10:37:01Z
2011-01-21T10:37:01Z
2009-08
artículo
Nanotechnology 20(33): 335501 (2009)
0957-4484
http://hdl.handle.net/10261/31415
10.1088/0957-4484/20/33/335501
http://dx.doi.org/10.13039/501100004837
http://dx.doi.org/10.13039/501100003339
http://dx.doi.org/10.13039/501100000780
eng
http://dx.doi.org/10.1088/0957-4484/20/33/335501
closedAccess
Institute of Physics Publishing
oai:digital.csic.es:10261/314162020-03-12T09:59:18Zcom_10261_89com_10261_3com_10261_10252col_10261_342col_10261_10253
2011-01-21T10:54:13Z
urn:hdl:10261/31416
Understanding the role of thiol and disulfide self-assembled DNA receptor monolayers for biosensing applications
Carrascosa, Laura G.
Martínez-Orellana, Lidia
Huttel, Yves
Román García, Elisa Leonor
Lechuga, Laura M.
Ministerio de Ciencia e Innovación (España)
Fundación Botín
Thiolated DNA
Biofunctionalization
Surface plasmon resonance biosensor
Nanomechanical biosensor
Fluorescence
XPS
12 páginas, 4 figuras, 1 tabla.
A detailed study of the immobilization of three differently sulfur-modified DNA receptors for biosensing applications is presented. The three receptors are DNA-(CH)n-SH-, DNA-(CH)n-SS-(CH)n-DNA, and DNA-(CH)n-SS-DMTO. Nanomechanical and surface plasmon resonance biosensors and fluorescence and radiolabelling techniques were used for the experimental evaluation. The results highlight the critical role of sulfur linker type in DNA self-assembly, affecting the kinetic adsorption and spatial distribution of DNA chains within the monolayer and the extent of chemisorption and physisorption. A spacer (mercaptohexanol, MCH) is used to evaluate the relative efficiencies of chemisorption of the three receptors by analysing the extent to which MCH can remove physisorbed molecules from each type of monolayer. It is demonstrated that –SH derivatization is the most suitable for biosensing purposes as it results in densely packed monolayers with the lowest ratio of physisorbed probes.
2011-01-21T10:54:13Z
2011-01-21T10:54:13Z
2010-04
artículo
European Biophysics Journal 39(10): 1433-1444 (2010)
0175-7571
http://hdl.handle.net/10261/31416
10.1007/s00249-010-0599-6
http://dx.doi.org/10.13039/501100004837
http://dx.doi.org/10.13039/501100006373
eng
http://dx.doi.org/10.1007/s00249-010-0599-6
closedAccess
Springer
oai:digital.csic.es:10261/339352021-06-14T08:05:33Zcom_10261_36com_10261_4com_10261_10252com_10261_3col_10261_289col_10261_10253
2011-03-30T09:58:52Z
urn:hdl:10261/33935
Cobalt dependence of the magneto-optical response in magnetoplasmonic nanodisks
González-Díaz, Juan B.
Sepúlveda, Borja
García-Martín, Antonio
Armelles Reig, Gaspar
European Commission
Ministerio de Ciencia e Innovación (España)
European Commission
Comunidad de Madrid
Ministerio de Ciencia e Innovación (España)
Consejo Superior de Investigaciones Científicas (España)
Cobalt
Gold
Kerr magneto-optical effect
Nanostructured materials
Plasmonics
Spectral line breadth
In this work, we study the plasmon-mediated enhancement of the magneto-optical (MO) activity in the case of Au/Co/Au nanodisks as a function of the Co content. We show that both the spectral shape and amplitude of the complex polar Kerr rotation are modified by the relative amount of gold (diamagnetic) and cobalt (ferromagnetic). We demonstrate that such shape modification is dictated by the predominance of the absorptive or dispersive part of the MO constant in each material, which is intimately related to the origin of their MO activity.
2011-03-30T09:58:52Z
2011-03-30T09:58:52Z
2010-07-30
artículo
Applied Physics Letters 97(4): 043114 (2010)
0003-6951
http://hdl.handle.net/10261/33935
10.1063/1.3474617
http://dx.doi.org/10.13039/501100003339
http://dx.doi.org/10.13039/100012818
http://dx.doi.org/10.13039/501100004837
http://dx.doi.org/10.13039/501100000780
eng
Publisher's version
http://dx.doi.org/10.1063/1.3474617
info:eu-repo/grantAgreement/EC/FP7/214107
openAccess
American Institute of Physics
oai:digital.csic.es:10261/359482016-07-01T09:35:09Zcom_10261_36com_10261_4com_10261_10252com_10261_3col_10261_289col_10261_10253
2011-05-23T11:44:26Z
urn:hdl:10261/35948
Random population model to explain the recombination dynamics in single InAs/GaAs quantum dots under selective optical pumping
Gomis-Bresco, J.
Muñoz-Matutano, G.
Martínez Pastor, Juan Pascual
Alén, Benito
Generalitat Valenciana
Ministerio de Ciencia e Innovación (España)
18 páginas, 3 tablas, 9 figuras.-- et al.
We model the time-resolved and time-integrated photoluminescence of a single InAs/GaAs quantum dot (QD) using a random population description. We reproduce the joint power dependence of the single QD exciton complexes(neutral exciton, neutral biexciton and charged trions). We use the model to investigate the selective optical pumping phenomenon, a predominance of the negative trion observed when the optical excitation is resonant to a nonintentional
impurity level. Our experiments and simulations determine that the negative charge confined in the QD after exciting resonance to the impurity level escapes in 10 ns.
2011-05-23T11:44:26Z
2011-05-23T11:44:26Z
2011-02-09
artículo
New Journal of Physics 13: 023022 (2011)
1367-2630
http://hdl.handle.net/10261/35948
10.1088/1367-2630/13/2/023022
http://dx.doi.org/10.13039/501100003359
http://dx.doi.org/10.13039/501100004837
eng
Publisher's version
http://dx.doi.org/10.1088/1367-2630/13/2/023022
Sí
openAccess
Institute of Physics Publishing
oai:digital.csic.es:10261/369562016-06-28T12:36:59Zcom_10261_89com_10261_3com_10261_10252col_10261_342col_10261_10253
2011-06-17T11:41:04Z
urn:hdl:10261/36956
Magnetism-Dependent Transport Phenomena in Hydrogenated Graphene: From Spin-Splitting to Localization Effects
Leconte, Nicolás
Soriano, David
Roche, Stephan
Ordejón, Pablo
Charlier, Jean-Christopher
Palacios, J. J.
Ministerio de Ciencia e Innovación (España)
Consejo Superior de Investigaciones Científicas (España)
Universidad de Alicante
Fonds de la Recherche Scientifique (Fédération Wallonie-Bruxelles)
Belgian Science Policy Office
Fédération Wallonie-Bruxelles
Agence Nationale de la Recherche (France)
Disordered graphene
Quantum transport
Metal-insulator transition
Ballistic transport
numerical simulation
Hydrogenation
Graphene spintronics
Hubbard-model
Transistors
“This document is the unedited Author’s version of a Submitted Work
that was subsequently accepted for publication in [JournalTitle],
copyright © American Chemical Society after peer review. To access
the final edited and published work see [insert ACS Articles on
Request author-directed link to Publisher website.
Spin-dependent transport in hydrogenated two-dimensional graphene is explored theoretically. Adsorbed atomic hydrogen Impurities can either induce a local antiferromagnetic, ferromagnetic, or nonmagnetic state depending on their density and relative distribution. To describe the various magnetic possibilities of hydrogenated graphene, a self-consistent Hubbard Hamiltonian, optimized by ab initio calculations, Is first solved in the mean field approximation for small graphene cells. Then, an efficient order N Kubo transport methodology is implemented, enabling large scale simulations of functionalized graphene. Depending on the underlying intrinsic magnetic ordering of hydrogen-induced spins, remarkably different transport features are predicted for the same Impurity concentration. Indeed, while the disordered nonmagnetic graphene system exhibits a transition from diffusive to localization regimes, the intrinsic ferromagnetic state exhibits unprecedented robustness toward quantum Interference, maintaining, for certain resonant energies, a quasiballistic regime up to the micrometer scale. Consequently, low temperature transport measurements could unveil the presence of a magnetic state in weakly hydrogenated graphene.
2011-06-17T11:41:04Z
2011-06-17T11:41:04Z
2011-05
artículo
ACS Nano 5 (5), 3987-3992 (2011)
1936-0851
http://hdl.handle.net/10261/36956
10.1021/nn200558d
http://dx.doi.org/10.13039/501100004837
http://dx.doi.org/10.13039/501100003339
http://dx.doi.org/10.13039/100009092
http://dx.doi.org/10.13039/501100002661
http://dx.doi.org/10.13039/501100001665
http://dx.doi.org/10.13039/501100002910
eng
http://dx.doi.org/10.1021/nn200558d
closedAccess
American Chemical Society
oai:digital.csic.es:10261/372262020-05-29T07:55:57Zcom_10261_10252com_10261_3col_10261_10253
2011-06-28T10:15:47Z
urn:hdl:10261/37226
La búsqueda del conocimiento a través de los grandes aceleradores de partículas
Lobo-Checa, Jorge
4 páginas, 2 figuras.
2011-06-28T10:15:47Z
2011-06-28T10:15:47Z
2010-06
artículo
Ciencia Rias Baixas 8: 24-27 (2010)
http://hdl.handle.net/10261/37226
spa
openAccess
Agrupación Astronómica Rías Baixas (Vigo)
oai:digital.csic.es:10261/372272020-05-29T07:55:57Zcom_10261_10252com_10261_3col_10261_10253
2011-06-28T10:19:23Z
urn:hdl:10261/37227
Nanociencia y Nanotechnología: un viaje fascinante al Nanocosmos
Lobo-Checa, Jorge
4 páginas. 3 figuras.
2011-06-28T10:19:23Z
2011-06-28T10:19:23Z
2010-01
artículo
Ciencia Rias Baixas 7: 33-36 (2010)
http://hdl.handle.net/10261/37227
spa
openAccess
Agrupación Astronómica Rías Baixas (Vigo)
oai:digital.csic.es:10261/391742022-04-21T11:47:48Zcom_10261_10252com_10261_3col_10261_10253
2011-08-31T11:18:12Z
urn:hdl:10261/39174
Robust Spin Polarization and Spin Textures on Stepped Au(111) Surfaces
Lobo-Checa, Jorge
Meier, Fabian
Dil, J. Hugo
Osterwalder, Jürg
Swiss National Science Foundation
European Commission
Consejo Superior de Investigaciones Científicas (España)
4 páginas, 3 figuras, 1 tabla.-- PACS numbers: 79.60.Bm, 72.25.-b, 73.20.At.-- et al.-- Trabajo presentado como comunicación oral al "10th International Conference on Atomically Controlled Surfaces, Interfaces and Nanostructures (ACSIN 10)" celebrado en Granada (España) del 21 al 25 de septiembre de 2009.
The influence of structural defects, in the form of step lattices, on the spin polarization of the spin-orbit split Shockley surface state of Au(111) has been investigated. Spin- and angle-resolved photoemission data from three vicinal surfaces with different step densities are presented. The spin splitting is preserved in all three cases, and there is no reduction of the spin polarization of individual subbands, including the umklapp bands induced by the step lattice. On the sample with the highest step density studied, where the wave functions are delocalized over several terraces, the spin splitting is enhanced substantially, likely as an effect of the effective surface corrugation as on related surface alloys. The spin texture shows in all cases spin polarization vectors tangential to the Fermi circles, with the same helicities as on Au(111).
2011-08-31T11:18:12Z
2011-08-31T11:18:12Z
2010
artículo
Physical Review Letters 104: 187602 (2010)
0031-9007
http://hdl.handle.net/10261/39174
10.1103/PhysRevLett.104.187602
1079-7114
http://dx.doi.org/10.13039/501100000780
http://dx.doi.org/10.13039/501100003339
eng
http://dx.doi.org/10.1103/PhysRevLett.104.187602
openAccess
American Physical Society
oai:digital.csic.es:10261/392662016-06-18T00:49:36Zcom_10261_10252com_10261_3com_10261_46col_10261_10253col_10261_299
2011-09-05T13:00:15Z
urn:hdl:10261/39266
Spontaneous self-assembly of Cu2O@PPynanowires and anisotropic crystals
Muñoz Rojas, David
Oró, Judith
Gómez-Romero, P.
Consejo Superior de Investigaciones Científicas (España)
European Commission
Ministerio de Ciencia e Innovación (España)
3 páginas, 3 figuras.
The hydrothermal reduction of commercial CuO by Py yields Cu2O@PPynanowires, branched nanostructures and bigger anisotropic crystals, which form spontaneously through oriented attachment in the absence of any capping agent or template.
2011-09-05T13:00:15Z
2011-09-05T13:00:15Z
2009
artículo
Chemical Communications (39): 5913-5915 (2009)
1359-7345
http://hdl.handle.net/10261/39266
10.1039/B910796G
1364-548X
http://dx.doi.org/10.13039/501100003339
http://dx.doi.org/10.13039/501100000780
http://dx.doi.org/10.13039/501100004837
eng
http://dx.doi.org/10.1039/B910796G
Sí
closedAccess
Royal Society of Chemistry (UK)
oai:digital.csic.es:10261/392702020-05-29T07:55:58Zcom_10261_10252com_10261_3col_10261_10253
2011-09-05T13:28:46Z
urn:hdl:10261/39270
STM fingerprint of molecule–adatom interactions in a self-assembled metal–organic surface coordination network on Cu(111)
Björk, Jonas
Matena, Manfred
Dyer, Matthew S.
Lobo-Checa, Jorge
Gade, Lutz H.
Jung, Thomas A.
Stöhr, Meike
Persson, Mats
European Commission
Swiss National Science Foundation
National Centres of Competence in Research (Switzerland)
Wolfermann-Naegeli Foundation
Swedish Research Council
7 páginas, 5 figuras, 3 tablas.-- El pdf del artículo es la versión pre-print.
A novel approach of identifying metal atoms within a metal–organic surface coordination network using scanning tunnelling microscopy (STM) is presented. The Cu adatoms coordinated in the porous surface network of 1,3,8,10-tetraazaperopyrene (TAPP) molecules on a Cu(111) surface give rise to a characteristic electronic resonance in STM experiments. Using density functional theory calculations, we provide strong evidence that this resonance is a fingerprint of the interaction between the molecules and the Cu adatoms. We also show that the bonding of the Cu adatoms to the organic exodentate ligands is characterised by both the mixing of the nitrogen lone-pair orbitals of TAPP with states on the Cu adatoms and the partial filling of the lowest unoccupied molecular orbital (LUMO) of the TAPP molecule. Furthermore, the key interactions determining the surface unit cell of the network are discussed.
2011-09-05T13:28:46Z
2011-09-05T13:28:46Z
2010
artículo
Physical Chemistry Chemical Physics 12(31): 8815-8821 (2010)
1463-9076
http://hdl.handle.net/10261/39270
10.1039/C003660A
1463-9084
http://dx.doi.org/10.13039/501100000780
http://dx.doi.org/10.13039/501100003950
eng
http://dx.doi.org/10.1039/C003660A
openAccess
Royal Society of Chemistry (UK)
oai:digital.csic.es:10261/393312020-05-29T07:55:58Zcom_10261_10252com_10261_3col_10261_10253
2011-09-07T09:50:10Z
urn:hdl:10261/39331
Two-Dimensional Phase Behavior of a Bimolecular Porphyrin System at the Solid−Vacuum Interface
Wintjes, Nikolai
Lobo-Checa, Jorge
Jung, Thomas A.
European Commission
Swiss National Science Foundation
Commission for Technology and Innovation (Switzerland)
SPECS Zurich
National Centres of Competence in Research (Switzerland)
European Commission
Swiss National Science Foundation
Wolfermann-Naegeli Foundation
Commission for Technology and Innovation (Switzerland)
SPECS Zurich
6 páginas, 3 figuras, 1 tabla.-- et al.-- Trabajo presentado como comunicación oral al congreso "Fuerzas y Tunel" celebrado en Tarragona (España) en septiembre de 2010: https://wiki.physik.fu-berlin.de/fyt10/home
The “in vacuo” self-assembly of a two-component porphyrin system on a metal surface is studied by means of scanning tunneling microscopy in the sub-monolayer regime. The observed self-assemblies are systematically analyzed by their dependence on the total coverage and on the ratio of the two components resulting in a two-dimensional phase diagram. In a small region within the parameter space, a mixed surface layer is observed. The results are discussed consistently on the basis of molecule−surface and molecule−molecule interactions as well as thermodynamic aspects, leading to a qualitative comprehension of the phase behavior of the two-dimensional bimolecular system.
2011-09-07T09:50:10Z
2011-09-07T09:50:10Z
2010
artículo
Journal of the American Chemical Society 132(21): 7306-7311 (2010)
0002-7863
http://hdl.handle.net/10261/39331
10.1021/ja909674e
1520-5126
http://dx.doi.org/10.13039/501100000780
http://dx.doi.org/10.13039/501100003950
eng
http://dx.doi.org/10.1021/ja909674e
closedAccess
American Chemical Society
oai:digital.csic.es:10261/402102016-05-30T12:43:43Zcom_10261_10252com_10261_3col_10261_10253
2011-09-28T12:24:15Z
urn:hdl:10261/40210
Divulgar o Vulgarizar
Gómez-Romero, P.
Artículo en revista de divulgación científica.
La divulgación resulta tan imprescindible para la sociedad tecnológica democrática como la gestión o la aplicación de la ciencia. Pero para garantizar su eficacia debe ser generosa, amena, ni demasiado profunda ni demasiado superficial, informada, coordinada entre científicos y periodistas, libre e independiente.
2011-09-28T12:24:15Z
2011-09-28T12:24:15Z
2008-07
trabajo de divulgación
Revista Agenda Viva 12: 43-44 (2008)
http://hdl.handle.net/10261/40210
spa
openAccess
Fundación Félix Rodríguez de la Fuente
oai:digital.csic.es:10261/432132016-05-04T11:32:27Zcom_10261_10252com_10261_3com_10261_46col_10261_10253col_10261_299
2011-12-12T11:54:28Z
urn:hdl:10261/43213
Carving at the Nanoscale: Sequential Galvanic Exchange and Kirkendall Growth at Room Temperature
González, Edgar
Arbiol, Jordi
Puntes, Víctor F.
Generalitat de Catalunya
Gobierno de Aragón
Ministerio de Ciencia y Tecnología (España)
Ministerio de Educación y Ciencia (España)
Report
Shape control of inorganic nanocrystals is important for understanding basic size- and shape-dependent scaling laws and is useful in a wide range of applications. With minor modifications in the chemical environment, it is possible to control the reaction and diffusion processes at room temperature, opening up a synthetic route for the production of polymetallic hollow nanoparticles with very different morphology and composition, obtained by the simultaneous or sequential action of galvanic replacement and the Kirkendall effect.
2011-12-12T11:54:28Z
2011-12-12T11:54:28Z
2011-12-09
artículo
Science 334(6061):1377-1380 (2011)
0036-8075
http://hdl.handle.net/10261/43213
10.1126/science.1212822
1095-9203
http://dx.doi.org/10.13039/501100002809
http://dx.doi.org/10.13039/501100006280
http://dx.doi.org/10.13039/501100010067
eng
http://dx.doi.org/10.1126/science.1212822
closedAccess
American Association for the Advancement of Science
oai:digital.csic.es:10261/440252021-07-23T08:48:23Zcom_10261_10252com_10261_3com_10261_115col_10261_10253col_10261_368
2012-01-09T11:02:03Z
urn:hdl:10261/44025
Plasmonic nickel nanoantennas
Chen, Jianing
Albella, Pablo
Alonso-González, Pablo
Bonanni, Valentina
Nogués, Josep
Dmitriev, Alexandre
Aizpurua, Javier
Hillenbrand, Rainer
European Commission
Ministerio de Ciencia e Innovación (España)
Eusko Jaurlaritza
Ministerio de Educación y Ciencia (España)
Swedish Foundation for Strategic Research
Swedish Research Council
Generalitat de Catalunya
7 páginas, 6 figuras.-- El pdf del artículo es la versión post-print.-- et al.
The fundamental optical properties of pure nickel nanostructures are studied by far-field extinction spectroscopy and optical near-field microscopy, providing direct experimental evidence of the existence of particle plasmon resonances predicted by theory. Experimental and calculated near-field maps allow for unambiguous identification of dipolar plasmon modes. By comparing calculated near-field and far-field spectra, dramatic shifts are found between the near-field and far-field plasmon resonances, which are much stronger than in gold nanoantennas. Based on a simple damped harmonic oscillator model to describe plasmonic resonances, it is possible to explain these shifts as due to plasmon damping.
2012-01-09T11:02:03Z
2012-01-09T11:02:03Z
2011-08
artículo
Small 7(16): 2341-2347 (2011)
1613-6810
http://hdl.handle.net/10261/44025
10.1002/smll.201100640
1613-6829
http://dx.doi.org/10.13039/501100000780
http://dx.doi.org/10.13039/501100004837
http://dx.doi.org/10.13039/501100002809
http://dx.doi.org/10.13039/501100003086
eng
Postprint
http://dx.doi.org/10.1002/smll.201100640
info:eu-repo/grantAgreement/EC/FP7/241818
openAccess
Wiley-VCH
oai:digital.csic.es:10261/440582017-02-22T13:20:50Zcom_10261_115com_10261_3com_10261_10252col_10261_368col_10261_10253
2012-01-09T14:18:51Z
urn:hdl:10261/44058
Localization, splitting, and mixing of field emission resonances induced by alkali metal clusters on Cu(100)
Stepanow, Sebastian
Mugarza, Aitor
Ceballos, Gustavo
Gambardella, Pietro
Aldazabal, Íñigo
Borisov, Andrei G.
Arnau, Andrés
European Research Council
Ministerio de Ciencia e Innovación (España)
Universidad del País Vasco
Generalitat de Catalunya
European Commission
Consejo Superior de Investigaciones Científicas (España)
12 páginas, 11 figuras.-- PACS number(s): 73.20.At, 73.20.Hb, 73.22.Dj, 68.37.Ef
We report on a joint scanning tunneling microscopy (STM) and theoretical wave packet propagation study of field emission resonances (FER’s) of nanosized alkali metal clusters deposited on a Cu(100) surface. In addition to FER’s of the pristine Cu(100) surface, we observe the appearance of island-induced resonances that are particularly well resolved for STM bias voltage values corresponding to electron energies inside the projected band gap of the substrate. The corresponding dI/dV maps reveal island-induced resonances of different nature. Their electronic densities are localized either inside the alkali cluster or on its boundaries. Our model calculations allow us to explain the experimental results as due to the coexistence and mixing of two kinds of island-induced states. On the one side, since the alkali work function is lower than that of the substrate, the nanosized alkali metal clusters introduce intrinsic localized electronic states pinned to the vacuum level above the cluster. These states can be seen as the FER’s of the complete alkali overlayer quantized by the cluster boundaries. On the other side, the attractive potential well due to the alkali metal cluster leads to two-dimensional (2D) localization of the FER’s of the Cu(100) surface, the corresponding split component of the resonances appearing below the bottom of the parent continuum. Our main conclusions are based on the attractive nature of the alkali ad-island potential. They are of general validity and, therefore, significant to understand electron confinement in 2D.
2012-01-09T14:18:51Z
2012-01-09T14:18:51Z
2011
artículo
Physical Review B 83(11): 115101 (2011)
1098-0121
http://hdl.handle.net/10261/44058
10.1103/PhysRevB.83.115101
1550-235X
http://dx.doi.org/10.13039/501100000781
http://dx.doi.org/10.13039/501100004837
http://dx.doi.org/10.13039/501100002809
http://dx.doi.org/10.13039/501100000780
http://dx.doi.org/10.13039/501100003339
eng
http://dx.doi.org/10.1103/PhysRevB.83.115101
openAccess
American Physical Society
oai:digital.csic.es:10261/441942015-04-30T11:09:29Zcom_10261_10252com_10261_3com_10261_89com_10261_115col_10261_10253col_10261_342col_10261_368
2012-01-12T11:57:35Z
urn:hdl:10261/44194
Growth and structure of self-assembled monolayers of a TTF derivative on Au(111)
Trelka, Marta
Lorente, Nicolás
Arnau, Andrés
Martín, Nazario
Otero, Roberto
Gallego, José M.
Miranda, Rodolfo
Ministerio de Ciencia e Innovación (España)
Comunidad de Madrid
Universidad del País Vasco
8 páginas, 13 figuras.-- et al.
The adsorption of a TTF derivative (2-[9-(1,3-dithiol-2-ylidene)anthracen-10(9H)-ylidene]-1,3-dithiole, exTTF) on Au(111) has been studied by a combination of scanning tunneling microscopy, photoelectron spectroscopy, and theoretical calculations. The results indicate that the molecule−substrate interaction is dominated by the S−Au bonds. However, due to conformational reasons, only one of the two dithiole rings is in close contact with the surface. As a consequence, the interaction with the Au surface is much smaller (less than half) the interaction of TTF with Au(111), where the four sulfur atoms are in direct contact.
2012-01-12T11:57:35Z
2012-01-12T11:57:35Z
2010
artículo
Journal of Physical Chemistry C 114(14): 6503–6510 (2010)
1932-7447
http://hdl.handle.net/10261/44194
10.1021/jp911839b
1932-7455
http://dx.doi.org/10.13039/501100004837
http://dx.doi.org/10.13039/100012818
eng
http://dx.doi.org/10.1021/jp911839b
closedAccess
American Chemical Society
oai:digital.csic.es:10261/442212021-10-27T07:22:37Zcom_10261_115com_10261_3com_10261_10252col_10261_368col_10261_10253
2012-01-13T09:21:02Z
urn:hdl:10261/44221
Mixed-valency signature in vibrational inelastic electron tunneling spectroscopy
Alducin Ochoa, Maite
Sánchez-Portal, Daniel
Arnau, Andrés
Lorente, Nicolás
Ministerio de Ciencia e Innovación (España)
Universidad del País Vasco
4 páginas, 3 figuras, 1 tabla.-- PACS numbers: 68.37.Ef, 72.10.-d, 72.25.-b, 79.20.Rf
Density functional theory simulations of the vibrational inelastic electron tunneling spectroscopy (IETS) of O2 on Ag(110) permits us to solve its unexplained IETS data [ Hahn et al. Phys. Rev. Lett. 85 1914 (2000)]. When semilocal density functional theory is corrected by including static intra-atomic correlations, the IETS simulations are in excellent agreement with the experiment. The unforeseen consequence of our calculations is that when adsorbed along the [001] direction, molecular O2 on Ag(110) is a mixed-valent system. This analysis of IETS unambiguously reveals the paramagnetic nature of O2 on Ag(110).
2012-01-13T09:21:02Z
2012-01-13T09:21:02Z
2010
artículo
Physical Review Letters 104(13): 136101 (2010)
0031-9007
http://hdl.handle.net/10261/44221
10.1103/PhysRevLett.104.136101
1079-7114
http://dx.doi.org/10.13039/501100004837
eng
http://dx.doi.org/10.1103/PhysRevLett.104.136101
openAccess
American Physical Society
oai:digital.csic.es:10261/442552021-10-27T07:22:38Zcom_10261_115com_10261_3com_10261_10252col_10261_368col_10261_10253
2012-01-13T13:50:27Z
urn:hdl:10261/44255
Role of molecular electronic structure in inelastic electron tunneling spectroscopy: O2 on Ag(110)
Monturet, Serge
Alducin Ochoa, Maite
Lorente, Nicolás
Ministerio de Ciencia e Innovación (España)
Universidad del País Vasco
10 páginas, 8 figuras, 2 tablas.-- PACS number(s): 68.37.-d, 72.10.-d, 72.25.-b, 79.20.Rf
Density-functional theory (DFT) simulations corrected by the intramolecular Coulomb repulsion U are performed to evaluate the vibrational inelastic electron tunneling spectroscopy (IETS) of O2 on Ag(110). In contrast to DFT calculations that predict a spinless adsorbed molecule, the inclusion of the U correction leads to the polarization of the molecule by shifting a spin-polarized molecular orbital toward the Fermi level. Hence, DFT+U characterizes O2 on Ag(110) as a mixed-valent system. This has an important implication in IETS because a molecular resonance at the Fermi level can imply a decrease in conductance while in the off-resonance case, an increase in conductance is the expected IETS signal. We use the lowest-order expansion on the electron-vibration coupling in order to evaluate the magnitude and spatial distribution of the inelastic signal. The final IET spectra are evaluated with the help of the self-consistent Born approximation and the effect of temperature and modulation-voltage broadening are explored. Our simulations reproduce the experimental data of O2 on Ag(110) [ J. R. Hahn, H. J. Lee and W. Ho Phys. Rev. Lett. 85 1914 (2000)] and give extra insight of the electronic and vibrational symmetries at play. This ensemble of results reveals that the IETS of O2 is more complicated that a simple decrease in conductance and cannot be ascribed to the effect of a single molecular-orbital resonance.
2012-01-13T13:50:27Z
2012-01-13T13:50:27Z
2010
artículo
Physical Review B 82(8): 085447 (2010)
1098-0121
http://hdl.handle.net/10261/44255
10.1103/PhysRevB.82.085447
1550-235X
http://dx.doi.org/10.13039/501100004837
eng
http://dx.doi.org/10.1103/PhysRevB.82.085447
openAccess
American Physical Society
oai:digital.csic.es:10261/445182016-05-03T07:49:00Zcom_10261_31com_10261_3com_10261_10252col_10261_284col_10261_10253
2012-01-20T10:54:25Z
urn:hdl:10261/44518
Alternating current magnetic susceptibility of a molecular magnet submonolayer directly patterned onto a micro superconducting quantum interference device
Martínez Pérez, M. J.
Bellido, Elena
Sesé Monclús, Javier
Drung, D.
Schurig, T.
Ruiz Molina, Daniel
Luis, Fernando
Ministerio de Ciencia e Innovación (España)
Consejo Superior de Investigaciones Científicas (España)
European Commission
Fundación Agencia Aragonesa para la Investigación y el Desarrollo
3 páginas, 3 figuras.-- et al.
We report the controlled integration, via dip pen nanolithography, of monolayer dots of ferritin-based CoO nanoparticles (12 μB) into the most sensitive areas of a microSQUID sensor. The nearly optimum flux coupling between these nanomagnets and the microSQUID improves the achievable sensitivity by a factor 102, enabling us to measure the linear susceptibility of the molecular array down to very low temperatures (13 mK). This method opens the possibility of applying ac susceptibility experiments to characterize two-dimensional arrays of single molecule magnets within a wide range of temperatures and frequencies.
2012-01-20T10:54:25Z
2012-01-20T10:54:25Z
2011-07
artículo
Applied Physics Letters 99(3): 032504 (2011)
0003-6951
http://hdl.handle.net/10261/44518
10.1063/1.3609859
1077-3118
http://dx.doi.org/10.13039/501100004837
http://dx.doi.org/10.13039/501100003339
http://dx.doi.org/10.13039/501100000780
http://dx.doi.org/10.13039/501100008767
eng
http://dx.doi.org/10.1063/1.3609859
openAccess
American Institute of Physics
oai:digital.csic.es:10261/445342016-02-17T09:21:54Zcom_10261_10252com_10261_3col_10261_10253
2012-01-20T12:48:24Z
urn:hdl:10261/44534
Comment on “Nanometer resolution piezoresponse force microscopy to study deep submicron ferroelectric and ferroelastic domains” [ Appl. Phys. Lett. 94, 162903 (2009)]
Vlooswijk, A. H. G.
Catalán, Gustau
Noheda, Beatriz
2 páginas, 1 figura.
2012-01-20T12:48:24Z
2012-01-20T12:48:24Z
2010-07
artículo
Applied Physics Letters 97(4): 046101 (2010)
0003-6951
http://hdl.handle.net/10261/44534
10.1063/1.3467005
1077-3118
eng
http://dx.doi.org/10.1063/1.3467005
openAccess
American Institute of Physics
oai:digital.csic.es:10261/445352016-02-17T09:44:53Zcom_10261_10252com_10261_3col_10261_10253
2012-01-20T12:55:24Z
urn:hdl:10261/44535
Continuously graded anisotropy in single (Fe53Pt47)100−xCux films
Nogués, Josep
Åkerman, Johan
Swedish Foundation for Strategic Research
Swedish Research Council
Göran Gustafsson Foundation
Knut and Alice Wallenberg Foundation
Generalitat de Catalunya
Ministerio de Ciencia e Innovación (España)
3 páginas, 3 figuras.-- et al.
We report on continuously graded anisotropy. During deposition, a compositional gradient is achieved by varying the Cu concentration from Cu-rich (Fe53Pt47)70Cu30 to Cu-free Fe53Pt47. The anisotropy gradient is then realized after annealing using the composition dependence of the low-anisotropy (A1) to high-anisotropy (L10) ordering temperature. The critical role of the annealing temperature on the resultant anisotropy gradient is investigated. Magnetic measurements support the creation of an anisotropy gradient in properly annealed films which exhibit both a reduced coercivity and moderate thermal stability. These results demonstrate that an anisotropy gradient can be realized, and tailored, in single continuous films without the need for multilayers.
2012-01-20T12:55:24Z
2012-01-20T12:55:24Z
2010
artículo
Applied Physics Letters 97(18): 182504 (2010)
0003-6951
http://hdl.handle.net/10261/44535
10.1063/1.3505521
1077-3118
http://dx.doi.org/10.13039/501100003426
http://dx.doi.org/10.13039/501100004063
http://dx.doi.org/10.13039/501100002809
http://dx.doi.org/10.13039/501100004837
eng
http://dx.doi.org/10.1063/1.3505521
openAccess
American Institute of Physics
oai:digital.csic.es:10261/445362017-02-22T11:25:43Zcom_10261_10252com_10261_3col_10261_10253
2012-01-20T13:09:02Z
urn:hdl:10261/44536
Correlated Electrons Step by Step: Itinerant-to-Localized Transition of Fe Impurities in Free-Electron Metal Hosts
Carbone, Carlo
Veronese, M.
Gardonio, S.
Grazioli, C.
Krull, C.
Balashov, Timofey
Mugarza, Aitor
Gambardella, Pietro
European Science Foundation
German Research Foundation
Foundation for Fundamental Research on Matter
Ministerio de Educación y Ciencia (España)
4 páginas, 5 figuras.-- PACS numbers: 79.60.-i, 71.10.Li, 73.20.Hb.-- et al.
High-resolution photoemission spectroscopy and ab initio calculations have been employed to analyze the onset and progression of d-sp hybridization in Fe impurities deposited on alkali metal films. The interplay between delocalization, mediated by the free-electron environment, and Coulomb interaction among d electrons gives rise to complex electronic configurations. The multiplet structure of a single Fe atom evolves and gradually dissolves into a quasiparticle peak near the Fermi level with increasing host electron density. The effective multiorbital impurity problem within the exact diagonalization scheme describes the whole range of hybridizations.
2012-01-20T13:09:02Z
2012-01-20T13:09:02Z
2010
artículo
Physical Review Letters 104(11): 117601 (2010)
0031-9007
http://hdl.handle.net/10261/44536
10.1103/PhysRevLett.104.117601
1079-7114
http://dx.doi.org/10.13039/501100000782
http://dx.doi.org/10.13039/501100001659
http://dx.doi.org/10.13039/501100001712
eng
http://dx.doi.org/10.1103/PhysRevLett.104.117601
openAccess
American Physical Society
oai:digital.csic.es:10261/445382016-02-17T06:46:47Zcom_10261_10252com_10261_3col_10261_10253
2012-01-20T13:18:00Z
urn:hdl:10261/44538
Current-voltage characteristics of graphene devices: Interplay between Zener-Klein tunneling and defects
Barreiro, Amelia
Bachtold, Adrian
Mauri, Francesco
European Science Foundation
European Commission
10 páginas, 12 figuras.-- PACS number(s): 72.80.Rj, 72.10.Fk, 73.50.Dn, 73.61.Wp.-- et al.
We report a theoretical/experimental study of current-voltage characteristics (I-V) of graphene devices near the Dirac point. The I-V can be described by a power law (I∝Vα with 1<α≤1.5). The exponent is higher when the mobility is lower. This superlinear I-V is interpreted in terms of the interplay between Zener-Klein transport, that is tunneling between different energy bands, and defect scattering. Surprisingly, the Zener-Klein tunneling is made visible by the presence of defects.
2012-01-20T13:18:00Z
2012-01-20T13:18:00Z
2010
artículo
Physical Review B 82(4): 045416 (2010)
1098-0121
http://hdl.handle.net/10261/44538
10.1103/PhysRevB.82.045416
1550-235X
http://dx.doi.org/10.13039/501100000782
http://dx.doi.org/10.13039/501100000780
eng
http://dx.doi.org/10.1103/PhysRevB.82.045416
openAccess
American Physical Society
oai:digital.csic.es:10261/445392016-02-17T05:35:26Zcom_10261_10252com_10261_3com_10261_46col_10261_10253col_10261_299
2012-01-20T13:28:30Z
urn:hdl:10261/44539
Density-wave instability in α-(BEDT-TTF)2KHg(SCN)4 studied by x-ray diffuse scattering and by first-principles calculations
Ordejón, Pablo
Canadell, Enric
Ministerio de Ciencia e Innovación (España)
Academy of Finland
Centro de Supercomputación de Cataluña
Centro de Supercomputación de Galicia
14 páginas, 8 figuras.-- PACS number(s): 71.18.+y, 71.45.Lr, 64.60.-i, 71.20.Rv.-- et al.
α-(BEDT-TTF)2KHg(SCN)4 develops a density wave ground state below 8 K whose origin is still debated. Here we report a combined x-ray diffuse scattering and first-principles density functional theory study supporting the charge density wave (CDW) scenario. In particular, we observe a triply incommensurate anharmonic lattice modulation with intralayer wave vector components which coincide within experimental errors to the maximum of the calculated Lindhard response function. A detailed study of the structural aspects of the modulation shows that the CDW instability in α-(BEDT-TTF)2KHg(SCN)4 is considerably more involved than those following a standard Peierls mechanism. We thus propose a microscopic mechanism where the CDW instability of the BEDT-TTF layer is triggered by the anion sublattice. Our mechanism also emphasizes the key role of the coupling of the BEDT-TTF and anion layers via the hydrogen bond network to set the global modulation.
2012-01-20T13:28:30Z
2012-01-20T13:28:30Z
2010
artículo
Physical Review B 82(13): 134116 (2010)
1098-012
http://hdl.handle.net/10261/44539
10.1103/PhysRevB.82.134116
1550-235X
http://dx.doi.org/10.13039/501100004837
http://dx.doi.org/10.13039/501100002341
eng
http://dx.doi.org/10.1103/PhysRevB.82.134116
openAccess
American Physical Society
oai:digital.csic.es:10261/445412016-02-17T05:35:28Zcom_10261_10252com_10261_3col_10261_10253
2012-01-20T13:40:05Z
urn:hdl:10261/44541
Edge magnetotransport fingerprints in disordered graphene nanoribbons
Roche, Stephan
Raquet, Bertrand
European Commission
Agence Nationale de la Recherche (France)
4 páginas, 4 figuras.-- PACS number(s): 72.80.Vp, 73.22.Pr, 75.47.-m.-- et al.
We report on (magneto)transport experiments in chemically derived narrow graphene nanoribbons under high magnetic fields (up to 60 T). Evidences of field-dependent electronic confinement are given and allow estimating the possible ribbon edge symmetry. A large positive magnetoconductance indicates a strong suppression of backscattering induced by the magnetic field. Such scenario is supported by tight-binding calculations which consider different types of underlying disorders (smooth edge disorder and long-range Coulomb scatterers).
2012-01-20T13:40:05Z
2012-01-20T13:40:05Z
2010
artículo
Physical Review B 82(41): 041413(R) (2010)
1098-0121
http://hdl.handle.net/10261/44541
10.1103/PhysRevB.82.041413
1550-235X
http://dx.doi.org/10.13039/501100000780
http://dx.doi.org/10.13039/501100001665
eng
http://dx.doi.org/10.1103/PhysRevB.82.041413
openAccess
American Physical Society
oai:digital.csic.es:10261/445422021-10-27T07:42:30Zcom_10261_31com_10261_3com_10261_10252col_10261_284col_10261_10253
2012-01-20T13:49:55Z
urn:hdl:10261/44542
Effect of crystalline disorder on quantum tunneling in the single-molecule magnet Mn12 benzoate
Carbonera, Chiara
Luis, Fernando
Sánchez-Marcos, J.
Camón, Agustín
Chaboy, Jesús
Ruiz Molina, Daniel
Imaz, Inhar
Ministerio de Ciencia e Innovación (España)
Diputación General de Aragón
Ministerio de Ciencia e Innovación (España)
German Research Foundation
German Academic Exchange Service
10 páginas, 9 figuras, 1 tabla.-- PACS number(s): 75.45.+j, 75.50.Xx, 75.60.Jk, 75.50.Kj.-- et al.
We report a detailed study of the effects that crystalline disorder has on the magnetic relaxation and quantum tunneling of Mn12 benzoate clusters. Thanks to the absence of interstitial molecules in the crystal structure of this molecular compound, we have been able to isolate the influence of long-range crystalline disorder. For this, we compare results obtained under two extreme situations: a crystalline sample and a nearly amorphous material. The results show that crystalline disorder affects little the anisotropy, magnetic relaxation, and quantum tunneling of these materials. It follows that disorder is not a necessary ingredient for the existence of magnetic quantum tunneling. The results unveil, however, a subtle influence of crystallinity via the modification of the symmetry of dipole-dipole interactions. The faster tunneling rates measured for the amorphous material are accounted for by a narrower distribution of dipolar bias in this material, as compared with the crystalline sample.
2012-01-20T13:49:55Z
2012-01-20T13:49:55Z
2010
artículo
Physical Review B 81(1): 014427 (2010)
1098-0121
http://hdl.handle.net/10261/44542
10.1103/PhysRevB.81.014427
1550-235X
http://dx.doi.org/10.13039/501100004837
http://dx.doi.org/10.13039/501100001655
http://dx.doi.org/10.13039/501100001659
eng
http://dx.doi.org/10.1103/PhysRevB.81.014427
openAccess
American Physical Society
oai:digital.csic.es:10261/445432016-02-17T08:36:56Zcom_10261_10252com_10261_3col_10261_10253
2012-01-20T14:00:13Z
urn:hdl:10261/44543
Efficient linear scaling method for computing the thermal conductivity of disordered materials
Li, Wu
Roche, Stephan
Cuniberti, Gianaurelio
German Research Foundation
European Centre for Emerging Materials and Processes Dresden
European Commission
Alexander von Humboldt Foundation
Agence Nationale de la Recherche (France)
Ministry of Education (South Korea)
9 páginas, 7 figuras.-- PACS number(s): 72.80.Vp, 72.15.Rn, 73.22.Pr.-- et al.
An efficient order-N real-space Kubo approach is developed for the calculation of the thermal conductivity of complex disordered materials. The method, which is based on the Chebyshev polynomial expansion of the time evolution operator and the Lanczos tridiagonalization scheme, efficiently treats the propagation of phonon wave packets in real space and the phonon diffusion coefficients. The mean free paths and the thermal conductance can be determined from the diffusion coefficients. These quantities can be extracted simultaneously for all frequencies, which is another advantage in comparison with approaches based on the Green’s function. Additionally, multiple scattering phenomena can be followed through the time dependence of the diffusion coefficient deep into the diffusive regime, and the onset of weak or strong phonon localization could possibly be revealed at low temperatures for thermal insulators. The accuracy of our computational scheme is demonstrated by comparing the calculated phonon mean free paths in isotope-disordered carbon nanotubes with Landauer simulations and analytical results. Then the upscalability of the method is illustrated by exploring the phonon mean free paths and the thermal conductance features of edge-disordered graphene nanoribbons having widths of ~20 nm and lengths as long as a micrometer, which are beyond the reach of other numerical techniques. It is shown that the phonon mean free paths of armchair nanoribbons are smaller than those of zigzag nanoribbons for the frequency range which dominates the thermal conductance at low temperatures. This computational strategy is applicable to higher-dimensional systems as well as to a wide range of materials.
2012-01-20T14:00:13Z
2012-01-20T14:00:13Z
2011
artículo
Physical Review B 83(15): 155416 (2011)
1098-0121
http://hdl.handle.net/10261/44543
10.1103/PhysRevB.83.155416
1550-235X
http://dx.doi.org/10.13039/501100001659
http://dx.doi.org/10.13039/501100000780
http://dx.doi.org/10.13039/100005156
http://dx.doi.org/10.13039/501100001665
http://dx.doi.org/10.13039/501100002701
eng
http://dx.doi.org/10.1103/PhysRevB.83.155416
openAccess
American Physical Society
oai:digital.csic.es:10261/445442016-02-17T06:46:48Zcom_10261_10252com_10261_3col_10261_10253
2012-01-20T14:17:31Z
urn:hdl:10261/44544
Engineering carbon chains from mechanically stretched graphene-based materials
Cuniberti, Gianaurelio
Roche, Stephan
Seifert, G.
European Commission
Free State of Saxony
Agence Nationale de la Recherche (France)
Alexander von Humboldt Foundation
4 páginas, 4 figuras.-- PACS number(s): 61.46.Km, 73.63.−b, 62.25.−g.-- et al.
The electrical response of graphene-based materials can be tailored under mechanical stress. We report different switching behaviors that take place in mechanically deformed graphene nanoribbons prior to the breakage of the junction. By performing tight-binding molecular dynamics, the study of structural changes of graphene nanoribbons with different widths is achieved, revealing that carbon chains are the ultimate bridges before the junction breaks. The electronic and transport calculations show that binary on/off states can be switched prior to and during breakage depending on the atomic details of the nanoribbon. This work supports the interpretation of recent experiments on nonvolatile memory element engineering based on graphene break junctions.
2012-01-20T14:17:31Z
2012-01-20T14:17:31Z
2011
artículo
Physical Review B 83(4): 041401(R) (2011)
1098-0121
http://hdl.handle.net/10261/44544
10.1103/PhysRevB.83.041401
1550-235X
http://dx.doi.org/10.13039/501100000780
http://dx.doi.org/10.13039/501100001665
http://dx.doi.org/10.13039/100005156
eng
http://dx.doi.org/10.1103/PhysRevB.83.041401
openAccess
American Physical Society
oai:digital.csic.es:10261/445452016-02-17T05:35:29Zcom_10261_10252com_10261_3col_10261_10253
2012-01-20T14:36:24Z
urn:hdl:10261/44545
Excitation of spin waves by tunneling electrons in ferromagnetic and antiferromagnetic spin-1/2 Heisenberg chains
Gauyacq, J. P.
Lorente, Nicolás
14 páginas, 14 figuras.-- PACS number(s): 68.37.Ef, 72.25.−b, 73.23.−b, 75.30.Ds
Excitation of finite chains of magnetic atoms adsorbed on a surface by tunneling electrons from a scanning tunneling microscope tip is studied using a Heisenberg Hamiltonian description of the magnetic couplings along the chain and a strong coupling approach to inelastic tunneling. The excitation probability of the magnetic levels is very high and the excitation spectra in chains of different lengths are very similar. The excitations in finite chains can be considered as spin waves quantized in the finite object. The energy and momentum spectra of the spin waves excited in the idealized infinite chain by tunneling electrons are determined from the results on the finite chains. Both ferromagnetic and antiferromagnetic couplings are considered, leading to very different results. In particular, in the antiferromagnetic case, excitations linked to the entanglement of the chain ground state are evidenced.
2012-01-20T14:36:24Z
2012-01-20T14:36:24Z
2011
artículo
Physical Review B 83(3): 155416 (2011)
1098-0121
http://hdl.handle.net/10261/44545
10.1103/PhysRevB.83.035418
1550-235X
eng
http://dx.doi.org/10.1103/PhysRevB.83.035418
openAccess
American Physical Society
oai:digital.csic.es:10261/445462016-02-17T05:35:30Zcom_10261_10252com_10261_3col_10261_10253
2012-01-20T14:58:35Z
urn:hdl:10261/44546
Experimental Spin Ratchet
Costache, Marius V.
Valenzuela, Sergio O.
arXiv:1103.0105v1
Spintronics relies on the ability to transport and use the spin properties of an electron rather than its charge. We describe a spin ratchet at the single-electron level that produces spin currents with no net bias or charge transport. Our device is based on the ground-state energetics of a single-electron transistor comprising a superconducting island connected to normal leads via tunnel barriers with different resistances that break spatial symmetry. We demonstrate spin transport and quantify the spin ratchet efficiency by using ferromagnetic leads with known spin polarization. Our results are modeled theoretically and provide a robust route to the generation and manipulation of pure spin currents.
2012-01-20T14:58:35Z
2012-01-20T14:58:35Z
2010-12
artículo
Science 330(6011): 1645-1648 (2010)
0036-8075
http://hdl.handle.net/10261/44546
10.1126/science.1196228
1095-9203
eng
Preprint
http://dx.doi.org/10.1126/science.1196228
Sí
openAccess
American Association for the Advancement of Science
oai:digital.csic.es:10261/445602016-02-17T06:42:54Zcom_10261_10252com_10261_3col_10261_10253
2012-01-23T09:16:52Z
urn:hdl:10261/44560
First-order reversal curve analysis of graded anisotropy FePtCu films
Nogués, Josep
Åkerman, Johan
Swedish Foundation for Strategic Research
Swedish Research Council
Göran Gustafsson Foundation
Knut and Alice Wallenberg Foundation
Foundation Blanceflor Boncompagni Ludovisi
Generalitat de Catalunya
Ministerio de Ciencia e Innovación (España)
Royal Swedish Academy of Sciences
3 páginas, 2 figuras.-- et al.
The reversal mechanisms of graded anisotropy FePtCu films have been investigated by alternating gradient magnetometer (AGM) and magneto-optical Kerr effect (MOKE) measurements with first-order reversal curve (FORC) techniques. The AGM-FORC analysis, which clearly shows the presence of soft and hard components, is unable to resolve how these phases are distributed throughout the film thickness. MOKE-FORC measurements, which preferentially probe the surface of the film, reveal that the soft components are indeed located toward the top surface. Combining AGM-FORC with the inherent surface sensitivity of MOKE-FORC analysis allows for a comprehensive analysis of heterogeneous systems such as graded materials.
2012-01-23T09:16:52Z
2012-01-23T09:16:52Z
2010
artículo
Applied Physics Letters 97(20): 202501 (2010)
0003-6951
http://hdl.handle.net/10261/44560
10.1063/1.3515907
1077-3118
http://dx.doi.org/10.13039/501100003426
http://dx.doi.org/10.13039/501100004063
http://dx.doi.org/10.13039/501100002809
http://dx.doi.org/10.13039/501100004837
http://dx.doi.org/10.13039/501100001725
http://dx.doi.org/10.13039/501100006358
eng
http://dx.doi.org/10.1063/1.3515907
openAccess
American Institute of Physics
oai:digital.csic.es:10261/445642017-02-22T13:20:22Zcom_10261_10252com_10261_3col_10261_10253
2012-01-23T09:39:19Z
urn:hdl:10261/44564
Giant spin and orbital moment anisotropies of a Cu-phthalocyanine monolayer
Stepanow, Sebastian
Mugarza, Aitor
Ceballos, Gustavo
Carbone, Carlo
Gambardella, Pietro
European Research Council
European Science Foundation
Ministerio de Ciencia e Innovación (España)
Generalitat de Catalunya
8 páginas, 4 figuras.-- -- PACS number(s): 75.70.Ak, 75.70.Tj, 78.70.Dm, 81.07.Pr.-- et al.
The magnetism of a Cu-phthalocyanine (CuPc) monolayer on Ag(100) was investigated using x-ray magnetic circular dichroism (XMCD) and ligand-field multiplet calculations. Contrary to other metal-Pc adsorbed on metals, we show that the local CuPc moment survives the interaction with the electronic states of the substrate and presents enhanced susceptibility with respect to bulk powder samples. Our measurements reveal extraordinary orbital moment anisotropy (500%) and an anisotropic spin dipole moment up to twice the isotropic spin in a metal-organic layer. A complete description of the orbital, spin, and spin-orbit operators is provided based on the XMCD sum rules.
2012-01-23T09:39:19Z
2012-01-23T09:39:19Z
2010
artículo
Physical Review B 82(1): 014405 (2010)
0957-4484
http://hdl.handle.net/10261/44564
10.1103/PhysRevB.82.014405
1361-6528
http://dx.doi.org/10.13039/501100000781
http://dx.doi.org/10.13039/501100000782
http://dx.doi.org/10.13039/501100004837
http://dx.doi.org/10.13039/501100002809
eng
http://dx.doi.org/10.1103/PhysRevB.82.014405
openAccess
American Physical Society
oai:digital.csic.es:10261/445652018-01-18T12:31:39Zcom_10261_10252com_10261_3col_10261_10253
2012-01-23T09:45:35Z
urn:hdl:10261/44565
Graphene on Ru(0001): Contact Formation and Chemical Reactivity on the Atomic Scale
Lorente, Nicolás
Berndt, Richard
Ministerio de Ciencia e Innovación (España)
European Commission
German Research Foundation
Fonds Schleswig-Holstein
4 páginas, 4 figuras.-- PACS numbers: 68.65.Pq, 68.37.Ef, 72.80.Vp.-- et al.
Graphene on Ru(0001) is contacted with Au tips of a cryogenic scanning tunneling microscope. The formation and conductance of single-atom contacts vary within the moiré unit cell. Density functional calculations reveal that elastic distortions of the graphene lattice occur at contact due to a selectively enhanced chemical reactivity of C atoms at hollow sites of Ru(0001). Concomitant quantum transport calculations indicate that the graphene-Ru distance determines the conductance variations.
2012-01-23T09:45:35Z
2012-01-23T09:45:35Z
2010
artículo
Physical Review Letters 105(23): 236101 (2010)
0031-9007
http://hdl.handle.net/10261/44565
10.1103/PhysRevLett.105.236101
1079-7114
http://dx.doi.org/10.13039/501100004837
http://dx.doi.org/10.13039/501100000780
http://dx.doi.org/10.13039/501100001659
eng
http://dx.doi.org/10.1103/PhysRevLett.105.236101
openAccess
American Physical Society
oai:digital.csic.es:10261/445662016-02-17T08:02:23Zcom_10261_10252com_10261_3col_10261_10253
2012-01-23T09:53:07Z
urn:hdl:10261/44566
Ground-state-cooling vibrations of suspended carbon nanotubes with constant electron current
Zippilli, Stefano
Bachtold, Adrian
Morigi, Giovanna
European Commission
European Science Foundation
Ministerio de Ciencia e Innovación (España)
Consejo Superior de Investigaciones Científicas (España)
German Research Foundation
9 páginas, 5 figuras.-- PACS number(s): 73.63.Kv, 85.85.+j, 63.22.Gh, 73.21.La
We investigate the efficiency of cooling the vibrations of a nanomechanical resonator, constituted by a partially suspended carbon nanotube and operating as double-quantum dot. The motion is brought to lower temperatures by tailoring the energy exchange via electromechanical coupling with single electrons, constantly flowing through the nanotube when a constant potential difference is applied at its extremes in the Coulomb-blockade regime. Ground-state cooling is possible at sufficiently high-quality factors, provided that the dephasing rate of electron transport within the double dot does not exceed the resonator frequency. For large values of the dephasing rates cooling can still be achieved by appropriately setting the tunable parameters.
2012-01-23T09:53:07Z
2012-01-23T09:53:07Z
2010
artículo
Physical Review B 81(20): 205408 (2010)
1098-0121
http://hdl.handle.net/10261/44566
10.1103/PhysRevB.81.205408
1550-235X
http://dx.doi.org/10.13039/501100000780
http://dx.doi.org/10.13039/501100000782
http://dx.doi.org/10.13039/501100004837
http://dx.doi.org/10.13039/501100003339
http://dx.doi.org/10.13039/501100001659
eng
http://dx.doi.org/10.1103/PhysRevB.81.205408
openAccess
American Physical Society
oai:digital.csic.es:10261/445672016-02-17T06:42:55Zcom_10261_10252com_10261_3col_10261_10253
2012-01-23T10:06:23Z
urn:hdl:10261/44567
Inelastic Transport in Vibrating Disordered Carbon Nanotubes: Scattering Times and Temperature-Dependent Decoherence Effects
Roche, Stephan
Hirose, Kenji
Ministry of Education, Culture, Sports, Science and Technology (Japan)
4 páginas, 4 figuras.-- PACS numbers: 73.63.Fg, 63.22.-m, 72.15.Lh.-- et al.
By using an order N quantum transport methodology, and treating on the same footing static and dynamical disorders, we report on the theoretical exploration of quantum interferences tuned by electron-phonon mediated decoherence mechanisms in disordered carbon nanotubes (with length up to 10 μm). This allows the extraction of inelastic scattering times together with temperature-dependent coherence lengths, which favorably compare with available experimental data at a quantitative level, and clarify the role of localization phenomena up to room temperature.
2012-01-23T10:06:23Z
2012-01-23T10:06:23Z
2010
artículo
Physical Review Letters 104(11): 116801 (2010)
0031-9007
http://hdl.handle.net/10261/44567
10.1103/PhysRevLett.104.116801
1079-7114
http://dx.doi.org/10.13039/501100001700
eng
http://dx.doi.org/10.1103/PhysRevLett.104.116801
openAccess
American Physical Society
oai:digital.csic.es:10261/445682016-02-17T06:42:57Zcom_10261_10252com_10261_3col_10261_10253
2012-01-23T10:21:25Z
urn:hdl:10261/44568
Landau theory of domain wall magnetoelectricity
Daraktchiev, Maren
Catalán, Gustau
Scott, James F.
12 páginas, 4 figuras.-- PACS number(s): 77.80.Dj
We calculate the exact analytical solution to the domain wall properties in a generic multiferroic system with two order parameters that are coupled biquadratically. This is then adapted to the case of a magnetoelectric multiferroic material such as BiFeO3, with a view to examine critically whether the domain walls can account for the enhancement of magnetization reported for thin films of this material, in view of the correlation between increasing magnetization and increasing volume fraction of domain walls as films become thinner. The present analysis can be generalized to describe a class of magnetoelectric devices based on domain walls rather than bulk properties.
2012-01-23T10:21:25Z
2012-01-23T10:21:25Z
2010
artículo
Physical Review B 81(22): 224118 (2010)
1098-0121
http://hdl.handle.net/10261/44568
10.1103/PhysRevB.81.224118
1550-235X
eng
http://dx.doi.org/10.1103/PhysRevB.81.224118
openAccess
American Physical Society
oai:digital.csic.es:10261/445702020-05-29T07:55:57Zcom_10261_10252com_10261_3col_10261_10253
2012-01-23T10:32:01Z
urn:hdl:10261/44570
LUMO photoemission lineshape in quasi-one-dimensional C60 chains
Lobo-Checa, Jorge
Osterwalder, Jürg
Swiss National Science Foundation
6 páginas, 4 figuras.-- PACS number(s): 71.20.Tx, 71.38.-k, 79.60.-i, 31.70.-f.-- et al.
The low-energy single-particle excitations of highly ordered C60 chains adsorbed on a vicinal copper substrate are investigated by angle-resolved photoemission spectroscopy. The interface state previously identified on C60/Cu(111) shows a one-dimensional dispersion on Cu(553). In contrast, no significant momentum dependence is detected for emission from the lowest unoccupied molecular orbital (LUMO). The LUMO displays similar phonon features as in C60/Cu(111) but it does not peak toward the Fermi level for all considered potassium dopings and its photoemission lineshape is broader than in any other monolayer system investigated so far. This behavior is not easily reconciled with existing theory and indicates that the one-dimensional character of the chains affects the electronic structure of the monolayer in an intricate way.
2012-01-23T10:32:01Z
2012-01-23T10:32:01Z
2010
artículo
Physical Review B 81(4): 045423 (2010)
1098-0121
http://hdl.handle.net/10261/44570
10.1103/PhysRevB.81.045423
1550-235X
eng
http://dx.doi.org/10.1103/PhysRevB.81.045423
openAccess
American Physical Society
oai:digital.csic.es:10261/445712016-02-17T06:29:19Zcom_10261_10252com_10261_3col_10261_10253
2012-01-23T10:48:57Z
urn:hdl:10261/44571
Magnetic anisotropy of Fe and Co ultrathin films deposited on Rh(111) and Pt(111) substrates: An experimental and first-principles investigation
Lehnert, Anne
Dennler, Samuel
Błoński, Piotr
Rusponi, S.
Etzkorn, Markus
Moulas, Géraud
Bencok, Peter
Gambardella, Pietro
Brune, H.
Hafner, Jürgen
Swiss National Science Foundation
Ministerio de Ciencia e Innovación (España)
Generalitat de Catalunya
European Science Foundation
23 páginas,15 figuras, 6 tablas.-- PACS number(s): 75.30.Gw, 75.75.-c, 71.15.Mb, 78.70.Dm
We report on a combined experimental and theoretical investigation of the magnetic anisotropy of Fe and Co ultrathin layers on strongly polarizable metal substrates. Monolayer (ML) films of Co and Fe on Rh(111) have been investigated in situ by x-ray magnetic circular dichroism (XMCD), magneto-optic Kerr effect, and scanning tunneling microscopy. The experiments show that both magnetic adlayers exhibit ferromagnetic order and enhanced spin and orbital moments compared to the bulk metals. The easy magnetization axis of 1 ML Co was found to be in plane, in contrast to Co/Pt(111), and that of 1 ML Fe out of plane. The magnetic anisotropy energy (MAE) derived from the magnetization curves of the Fe and Co films is one order of magnitude larger than the respective bulk values. XMCD spectra measured at the Rh M2,3 edges evidence significant magnetic polarization of the Rh(111) surface with the induced magnetization closely following that of the overlayer during the reversal process. The easy axis of 1–3 ML Co/Rh(111) shows an oscillatory in-plane/out-of-plane behavior due to the competition between dipolar and crystalline MAE. We present a comprehensive theoretical treatment of the magnetic anisotropy of Fe and Co layers on Rh(111) and Pt(111) substrates. For free-standing hexagonally close-packed monolayers the MAE is in plane for Co and out of plane for Fe. The interaction with the substrate inverts the sign of the electronic contribution to the MAE, except for Fe/Rh(111), where the MAE is only strongly reduced. For Co/Rh(111), the dipolar contribution outweighs the band contribution, resulting in an in-plane MAE in agreement with experiment while for Co/Pt(111) the larger band contribution dominates, resulting in an out-of-plane MAE. For Fe films however, the calculations predict for both substrates an in-plane anisotropy in contradiction to the experiment. At least for Fe/Pt(111) comparison of theory and experiment suggests that the magnetic structure of the adlayer is more complex than the homogenous ferromagnetic order assumed in the calculations. The angular momentum and layer-resolved contributions of the overlayer and substrate to the MAE and orbital moment anisotropy are discussed with respect to the anisotropic hybridization of the 3d, 4d, and 5d electron states and vertical relaxation. The role of technically relevant parameters such as the thickness of the surface slab, density of k points in the Brillouin zone, and electron-density functionals is carefully analyzed.
2012-01-23T10:48:57Z
2012-01-23T10:48:57Z
2010
artículo
Physical Review B 82(9): 014405 (2010)
1098-0121
http://hdl.handle.net/10261/44571
10.1103/PhysRevB.82.094409
1550-235X
http://dx.doi.org/10.13039/501100004837
http://dx.doi.org/10.13039/501100002809
http://dx.doi.org/10.13039/501100000782
eng
http://dx.doi.org/10.1103/PhysRevB.82.094409
openAccess
American Physical Society
oai:digital.csic.es:10261/445722016-02-17T06:42:58Zcom_10261_10252com_10261_3com_10261_46col_10261_10253col_10261_299
2012-01-23T10:59:59Z
urn:hdl:10261/44572
Magnetic transitions induced by tunneling electrons in individual adsorbed M-phthalocyanine molecules (M=Fe and Co)
Gauyacq, J. P.
Novaes, Frederico D.
Lorente, Nicolás
Ministerio de Ciencia e Innovación (España)
9 páginas, 7 figuras.-- PACS number(s): 75.75.-c, 74.55.+v, 75.30.Gw, 31.15.A-
We report on a theoretical study of magnetic transitions induced by tunneling electrons in individual adsorbed M-Phthalocyanine (M-Pc) molecules where M is a metal atom: Fe-Pc on a Cu(110)(2×1)-O surface and Co-Pc layers on Pb(111) islands. The magnetic transitions correspond to the change in orientation of the spin angular momentum of the metal ion with respect to the surroundings and possibly an applied magnetic field. The adsorbed Fe-Pc system is studied with a density-functional-theory-transport approach showing that (i) the magnetic structure of the Fe atom in the adsorbed Fe-Pc is quite different from that of the free Fe atom or of other adsorbed Fe systems and (ii) that injection of electrons (holes) into the Fe atom in the adsorbed Fe-Pc molecule dominantly involves the Fe 3dz2 orbital. These results fully specify the magnetic structure of the system and the process responsible for magnetic transitions. The dynamics of the magnetic transitions induced by tunneling electrons is treated in a strong-coupling approach. The Fe-Pc treatment is extended to the Co-Pc case. The present calculations accurately reproduce the strength of the magnetic transitions as observed by magnetic inelastic electron tunneling spectroscopy experiments; in particular, the dominance of the inelastic current in the conduction of the adsorbed M-Pc molecule is accounted for.
2012-01-23T10:59:59Z
2012-01-23T10:59:59Z
2010
artículo
Physical Review B 81(16): 165423 (2010)
1098-0121
http://hdl.handle.net/10261/44572
10.1103/PhysRevB.81.165423
1550-235X
http://dx.doi.org/10.13039/501100004837
eng
http://dx.doi.org/10.1103/PhysRevB.81.165423
openAccess
American Physical Society
oai:digital.csic.es:10261/445752016-02-17T08:44:43Zcom_10261_10252com_10261_3col_10261_10253
2012-01-23T11:15:34Z
urn:hdl:10261/44575
Magnetocrystalline anisotropy energy of Co and Fe adatoms on the (111) surfaces of Pd and Rh
Błoński, Piotr
Lehnert, Anne
Dennler, Samuel
Rusponi, S.
Etzkorn, Markus
Moulas, Géraud
Bencok, Peter
Gambardella, Pietro
Brune, H.
Hafner, Jürgen
Austrian Science Fund
Swiss National Science Foundation
European Science Foundation
Ministerio de Ciencia e Innovación (España)
Generalitat de Catalunya
18 páginas, 7 figuras, 6 tablas.-- PACS number(s): 75.30.Gw, 75.75.-c, 71.15.Mb, 78.70.Dm
We performed a combined theoretical and experimental investigation of the orbital magnetism and magnetocrystalline anisotropy of isolated Co and Fe adatoms on Pd(111) and Rh(111). Theoretical calculations of the spin and orbital moments are based on ab initio spin-polarized density-functional theory (DFT) including a self-consistent treatment of spin-orbit coupling. The calculations use a slab model to represent the adsorbate/substrate complex and allow for a complete structural relaxation leading to a strong inward displacement of the adatom and modest vertical and lateral relaxations in the substrate atoms. Compared to an idealized geometry where the atoms are kept on bulk lattice positions up to the surface, relaxation leads to a much stronger adatom/ligand hybridization. This is also reflected in the results for orbital moments and magnetocrystalline anisotropy energy (MAE). The enhanced hybridization leads to strong quenching of the adatom orbital moments but also to the formation of large induced spin and orbital moments in the substrate. As a consequence, we find that the substrate contribution to the MAE is much more important than estimated before on the basis of studies using an idealized geometry. We also find the surprising result that the MAE strongly depends on the adsorption site. The magnitude and even the sign of the MAE change for adatoms on face-centered cubic with respect to the ones on hexagonal close-packed hollow sites on the (111) surface. The dependence of the MAE on the combination of adatom and substrate has been analyzed in terms of the electronic structure, leading to a sound physical picture of the origin of the MAE. A fundamental problem, however, is the correct prediction of the size of the orbital moments of the adatoms. We suggest that this problem can be solved only via post-DFT corrections introducing an orbital dependence of the exchange potential. The theoretical results are compared to site-averaged, element-specific x-ray magnetic circular dichroism (XMCD) measurements. Low-temperature XMCD spectra and magnetization curves reveal weak out-of-plane anisotropy for Fe adatoms on both substrates. Interestingly, Co adatoms on Rh(111) present in-plane anisotropy with MAE of about −0.6 meV, contrary to the known out-of-plane anisotropy of Co on Pd(111) and Pt(111). The orbital to spin magnetic-moment ratio measured by XMCD shows that the Co adatoms present much stronger orbital magnetization components compared to Fe. The connection between orbital moments and MAE is discussed at the theoretical level including the contribution of the induced substrate magnetization.
2012-01-23T11:15:34Z
2012-01-23T11:15:34Z
2010
artículo
Physical Review B 81(10): 104426 (2010)
1098-0121
http://hdl.handle.net/10261/44575
10.1103/PhysRevB.81.104426
1550-235X
http://dx.doi.org/10.13039/501100002428
http://dx.doi.org/10.13039/501100000782
http://dx.doi.org/10.13039/501100004837
http://dx.doi.org/10.13039/501100002809
eng
http://dx.doi.org/10.1103/PhysRevB.81.104426
openAccess
American Physical Society
oai:digital.csic.es:10261/445762016-02-17T06:58:31Zcom_10261_10252com_10261_3com_10261_89col_10261_10253col_10261_342
2012-01-23T11:21:52Z
urn:hdl:10261/44576
Magnetoresistance and magnetic ordering fingerprints in hydrogenated graphene
Soriano, David
Leconte, Nicolás
Ordejón, Pablo
Charlier, Jean-Christopher
Palacios, J. J.
Roche, Stephan
Ministerio de Ciencia e Innovación (España)
Universidad de Alicante
Consejo Superior de Investigaciones Científicas (España)
4 páginas, 4 figuras.-- PACS numbers: 72.80.Vp, 73.20.Hb, 85.75.-d
Spin-dependent features in the conductivity of graphene, chemically modified by a random distribution of hydrogen adatoms, are explored theoretically. The spin effects are taken into account using a mean-field self-consistent Hubbard model derived from first-principles calculations. A Kubo transport methodology is used to compute the spin-dependent transport fingerprints of weakly hydrogenated graphene-based systems with realistic sizes. Conductivity responses are obtained for paramagnetic, antiferromagnetic, or ferromagnetic macroscopic states, constructed from the mean-field solutions obtained for small graphene supercells. Magnetoresistance signals up to ∼7% are calculated for hydrogen densities around 0.25%. These theoretical results could serve as guidance for experimental observation of induced magnetism in graphene.
2012-01-23T11:21:52Z
2012-01-23T11:21:52Z
2011
artículo
Physical Review Letters 107(1): 016602 (2011)
0031-9007
http://hdl.handle.net/10261/44576
10.1103/PhysRevLett.107.016602
1079-7114
http://dx.doi.org/10.13039/501100004837
http://dx.doi.org/10.13039/100009092
http://dx.doi.org/10.13039/501100003339
eng
Publisher's version
http://dx.doi.org/10.1103/PhysRevLett.107.016602
info:eu-repo/grantAgreement/EC/FP7/211956
openAccess
American Physical Society
oai:digital.csic.es:10261/445772016-02-17T08:32:46Zcom_10261_10252com_10261_3col_10261_10253
2012-01-23T11:31:57Z
urn:hdl:10261/44577
Magnetoresistance in disordered graphene: The role of pseudospin and dimensionality effects unraveled
Roche, Stephan
Agence Nationale de la Recherche (France)
European Commission
Fondation Nanosciences
6 páginas, 5 figuras.-- PACS numbers: 72.80.Vp, 72.15.Rn, 73.63.-b.-- El pdf del artículo es la versión pre-print:arXiv:1101.4754v1.-- et al.
We report a theoretical low-field magnetotransport study unveiling the effect of pseudospin in realistic models of weakly disordered graphene-based materials. Using an efficient Kubo simulation method, and simulating the effect of charges trapped in the oxide, different magnetoconductance fingerprints are numerically obtained for system sizes as large as 0.3 μm2, containing tens of millions of carbon atoms. In two-dimensional graphene, a strong valley mixing is found to irreparably yield a positive magnetoconductance (weak localization), whereas crossovers from positive to negative magnetoconductance (weak antilocalization) are obtained by reducing the disorder strength down to the ballistic limit. In sharp contrast, graphene nanoribbons with lateral size as large as 10 nm show no sign of weak antilocalization, even for very small disorder strength. Our results rationalize the emergence of a complex phase diagram of magnetoconductance fingerprints, shedding new light on the microscopical origin of pseudospin effects.
2012-01-23T11:31:57Z
2012-01-23T11:31:57Z
2011
artículo
EPL 94(4): 47006 (2011)
0295-5075
http://hdl.handle.net/10261/44577
10.1209/0295-5075/94/47006
1286-4854
http://dx.doi.org/10.13039/501100001665
http://dx.doi.org/10.13039/501100000780
http://dx.doi.org/10.13039/100007357
eng
http://dx.doi.org/10.1209/0295-5075/94/47006
openAccess
Institute of Physics Publishing
oai:digital.csic.es:10261/445792017-02-22T09:38:16Zcom_10261_10252com_10261_3col_10261_10253
2012-01-23T11:40:05Z
urn:hdl:10261/44579
Magnetotransport in disordered graphene exposed to ozone: From weak to strong localization
Moser, Joel
Tao, Haihua
Roche, Stephan
Alzina, Francesc
Sotomayor Torres, C. M.
Bachtold, Adrian
European Science Foundation
European Commission
Ministerio de Ciencia e Innovación (España)
6 páginas, 7 figuras.-- PACS number(s): 72.80.Vp, 72.15.Rn
We present a magnetotransport study of graphene samples into which a mild disorder was introduced by exposure to ozone. Unlike the conductivity of pristine graphene, the conductivity of graphene samples exposed to ozone becomes very sensitive to temperature: it decreases by more than three orders of magnitude between 100 and 1 K. By varying either an external gate voltage or temperature, we continuously tune the transport properties from the weak to the strong localization regime. We show that the transition occurs as the phase coherence length becomes comparable to the localization length. We also highlight the important role of disorder-enhanced electron-electron interaction on the resistivity.
2012-01-23T11:40:05Z
2012-01-23T11:40:05Z
2010
artículo
Physical Review B 81(20): 205445 (2010)
1098-0121
http://hdl.handle.net/10261/44579
10.1103/PhysRevB.81.205445
1550-235X
http://dx.doi.org/10.13039/501100000782
http://dx.doi.org/10.13039/501100000780
http://dx.doi.org/10.13039/501100004837
eng
http://dx.doi.org/10.1103/PhysRevB.81.205445
openAccess
American Physical Society
didl///col_10261_10253/100