Charge transport through spin-polarized tunnel junction between two spin-split superconductors

We investigate transport properties of junctions between two spin-split superconductors linked by a spin-polarized tunneling barrier. The spin-splitting fields in the superconductors (S) are induced by adjacent ferromagnetic insulating (FI) layers with arbitrary magnetization. The aim of this study...

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Bibliographic Details
Published in:Physical review. B 2019-11, Vol.100 (18), p.1, Article 184501
Main Authors: Rouco, Mikel, Chakraborty, Subrata, Aikebaier, Faluke, Golovach, Vitaly N., Strambini, Elia, Moodera, Jagadeesh S., Giazotto, Francesco, Heikkilä, Tero T., Bergeret, F. Sebastian
Format: Article
Language:English
Subjects:
Charge transport
Ferromagnetism
Green's functions
Josephson junctions
Magnetic anisotropy
Mathematical morphology
Order parameters
Resistance
Splitting
Superconductor junctions
Superconductors
Transport properties
Tunnel junctions
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Summary:We investigate transport properties of junctions between two spin-split superconductors linked by a spin-polarized tunneling barrier. The spin-splitting fields in the superconductors (S) are induced by adjacent ferromagnetic insulating (FI) layers with arbitrary magnetization. The aim of this study is twofold. On the one hand, we present a theoretical framework based on the quasiclassical Green's functions to calculate the Josephson and quasiparticle current through the junctions in terms of the different parameters characterizing it. Our theory predicts qualitative new results for the tunneling differential conductance, dI/dV, when the spin-splitting fields of the two superconductors are noncollinear. We also discuss how junctions based on FI/S can be used to realize anomalous Josephson junctions with a constant geometric phase shift in the current-phase relation. As a result, they may exhibit spontaneous triplet supercurrents in the absence of a phase difference between the S electrodes. On the other hand, we show results of planar tunneling spectroscopy of a EuS/Al/AlOx/EuS/Al junction and use our theoretical model to reproduce the obtained dI/dV curves. Comparison between theory and experiment reveals information about the intrinsic parameters of the junction, such as the size of the superconducting order parameter, spin-splitting fields and spin relaxation, and also about properties of the two EuS films, such as their morphology, domain structure, and magnetic anisotropy.
ISSN:2469-9950
2469-9969
DOI:10.1103/PhysRevB.100.184501