Interplay between Yu-Shiba-Rusinov states and multiple Andreev reflections

Year: 2020

Authors: Villas A., Klees R.L., Huang H., Ast C.R., Rastelli G., Belzig W., Cuevas J.C.

Autors Affiliation: Univ Autonoma Madrid, Dept Fis Teor Mat Condensada, E-28049 Madrid, Spain; Univ Autonoma Madrid, Condensed Matter Phys Ctr IFIMAC, E-28049 Madrid, Spain; Univ Konstanz, Fachbereich Phys, D-78457 Constance, Germany; Max Planck Inst Festkorperforsch, Heisenbergstr 1, D-70569 Stuttgart, Germany; Univ Konstanz, Zukunftskolleg, D-78457 Constance, Germany

Abstract: Motivated by recent scanning tunneling microscopy experiments on single magnetic impurities on superconducting surfaces, we present here a comprehensive theoretical study of the interplay between Yu-Shiba-Rusinov bound states and (multiple) Andreev reflections. Our theory is based on a combination of an Anderson model with broken spin degeneracy and nonequilibrium Green?s function techniques that allows us to describe the electronic transport through a magnetic impurity coupled to superconducting leads for arbitrary junction transparency. Using this combination, we are able to elucidate the different tunneling processes that give a significant contribution to the subgap transport. In particular, we predict the occurrence of a large variety of Andreev reflections mediated by Yu-Shiba-Rusinov bound states that clearly differ from the standard Andreev processes in nonmagnetic systems. Moreover, we provide concrete guidelines on how to experimentally identify the subgap features originating from these tunneling events. Overall, our work provides new insight into the role of the spin degree of freedom in Andreev transport physics.

Journal/Review: PHYSICAL REVIEW B

Volume: 101 (23)      Pages from: 235445  to:

More Information: The authors would like to thank Alfredo Levy Yeyati, Joachim Ankerhold, Ciprian Padurariu, and Bjorn Kubala for insightful discussions. A.V. and J.C.C. acknowledge funding from the Spanish Ministry of Economy and Competitiveness (MINECO) (Contract No. FIS2017-84057-P). This work was funded in part by the ERC Consolidator Grant AbsoluteSpin (Grant No. 681164) and by the Center for Integrated Quantum Science and Technology (IQST). R.L.K., W.B., and G.R. acknowledge support by the DFG through SFB 767 and Grant No. RA 2810/1. J.C.C. also acknowledges support via the Mercator Program of the DFG in the frame of the SFB 767.
KeyWords: Mesoscopic superconductivity
DOI: 10.1103/PhysRevB.101.235445

Citations: 16
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