Please use this identifier to cite or link to this item:
logo share SHARE logo core CORE BASE
Visualizar otros formatos: MARC | Dublin Core | RDF | ORE | MODS | METS | DIDL | DATACITE

Invite to open peer review

Coexistence of superconductivity and spin-splitting fields in superconductor/ferromagnetic insulator bilayers of arbitrary thickness

AuthorsHijano, Alberto CSIC ORCID CVN; Ilić, Stefan CSIC ORCID; Rouco, Mikel CSIC ORCID; González-Orellana, Carmen CSIC ORCID; Ilyn, Max CSIC ORCID; Rogero, Celia CSIC ORCID; Virtanen, Pauli; Heikkilä, T. T.; Khorshidian, Sara; Spies, Maria; Ligato, Nadia; Giazotto, Francesco; Strambini, Elia; Bergeret, F. S. CSIC ORCID
Issue Date2021
PublisherAmerican Physical Society
CitationPhysical Review Research 3(2): 023131 (2021)
AbstractFerromagnetic insulators (FI) can induce a strong exchange field in an adjacent superconductor (S) via the magnetic proximity effect. This manifests as spin splitting of the BCS density of states of the superconductor, an important ingredient for numerous superconducting spintronics applications and the realization of Majorana fermions. A crucial parameter that determines the magnitude of the induced spin splitting in FI/S bilayers is the thickness of the S layer d: In very thin samples, the superconductivity is suppressed by the strong magnetism. By contrast, in very thick samples, the spin splitting is absent at distances away from the interface. In this work, we calculate the density of states and critical exchange field of FI/S bilayers of arbitrary thickness. From here, we determine the range of parameters of interest for applications, where the exchange field and superconductivity coexist. We show that for d>3.0ξs, the paramagnetic phase transition is always of the second order, in contrast to the first-order transition in thinner samples at low temperatures. Here ξs is the superconducting coherence length. Finally, we compare our theory with the tunneling spectroscopy measurements in several EuS/Al/AlOx/Al samples. If the Al film in contact with the EuS is thinner than a certain critical value, we do not observe superconductivity, whereas, in thicker samples, we find evidence of a first-order phase transition induced by an external field. The complete transition is preceded by a regime in which normal and superconducting regions coexist. We attribute this mixed phase to inhomogeneities of the Al film thickness and the presence of superparamagnetic grains at the EuS/Al interface with different switching fields. The steplike evolution of the tunnel-barrier magnetoresistance supports this assumption. Our results demonstrate on the one hand, the important role of the S layer thickness, which is particularly relevant for the fabrication of high-quality samples suitable for applications. On the other hand, the agreement between theory and experiment demonstrates the accuracy of our theory, which, originally developed for homogeneous situations, is generalized to highly inhomogeneous systems.
Publisher version (URL)
Appears in Collections:(CFM) Artículos

Files in This Item:
File Description SizeFormat
coexisthick.pdf1,95 MBAdobe PDFThumbnail
Show full item record

CORE Recommender


checked on May 22, 2024


checked on Feb 16, 2024

Page view(s)

checked on May 25, 2024


checked on May 25, 2024

Google ScholarTM




This item is licensed under a Creative Commons License Creative Commons