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Title

Topological surface states of ternary chalcogenides probed by ARPES

AuthorsKimura, A.; Kuroda, K.; Ye, M.; Miyahara, H.; Eremeev, S. V.; Krasovskii, E. E.; Chulkov, Eugene V. ; Arita, M.; Miyamoto, Koji; Okuda, Taichi; Shimada, K.; Ueda, Y.; Namatame, H.; Taniguchi, M.
Issue Date2012
CitationICSFS-16 (2012)
AbstractThree-dimensional topological insulators (3D TIs) recently emerge as a new state of quantum matter, which can be topologically classified with Z2 topological invariants. It possesses a massless Dirac Fermion in a bulk energy gap whose spin orientations are locked with electron momentum, resulting in a helical spin texture. A number of 3D TIs have been intensively studied, among which Bi2Se3 has been regarded as one of the most promising candidates for potential applications in ultra-low power consumption quantum devices that can work stably at room temperature due to a sufficiently large bulk energy gap. Therefore, a significant effort has been made towards spintronic applications, but the surface contribution to conduction was hardly observed. This stimulates us to search for new 3D TIs possessing more ideal Dirac Fermions sufficiently isolated from the bulk continuum as actually predicted in several ternary compounds. Here we have studied the surface Dirac cones of several ternary chalcogenides including TlBiSe2 and PbBi2Te4 by high-resolution angle resolved photoemission spectroscopy using synchrotron radiation at Hiroshima Synchrotron Radiation Center (HiSOR). The single topological surface state is confirmed to be present at the surface Brillouin zone (SBZ) center for TlBiSe2. The Dirac cone is practically ideal especially near the Dirac point and its velocity is larger than for Bi2Se3. There are no bulk continuum states that energetically overlap with the DP, which means that the scattering channel from the topological surface state to the bulk continuum is suppressed. We have also clarified that PbBi2Te4 is the 3D TI, accompanying a single Dirac cone at the SBZ center. The size of the Fermi surface contours are significantly large in the bulk energy gap region. Besides, this material is found to have a Z2 topological invariant 1; (111). These novel findings pave an effective way for controlling the group velocity with sufficiently large spin current density by tuning the chemical potential in the topological quantum transport region
DescriptionTrabajo presentado a la "16th International Conference on Solid Films and Surfaces" celebrada en Genova (Italia) del 1 al 6 de julio de 2012.
URIhttp://hdl.handle.net/10261/103066
Appears in Collections:(CFM) Comunicaciones congresos
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