Berlin 2018 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 34: Superconductivity: Tunneling and Josephson Junctions

TT 34.9: Vortrag

Dienstag, 13. März 2018, 12:00–12:15, H 2053

Yu-Shiba-Rusinov states in magnetic Josephson junctions — •Andreas Costa, Denis Kochan, and Jaroslav Fabian — University of Regensburg, 93040 Regensburg, Germany

Superconductivity and ferromagnetism are two nominally antagonistic states of matter, which lead to extraordinary physical phenomena when combined in one system. Perhaps most striking is the emergence of 0-π transitions in magnetic Josephson junctions. We study the bound state spectrum in S/I/S Josephson junctions in which the interlayer (I) hosts point-like scalar and magnetic impurities. In addition to Andreev-like subgap states, stemming from the coherent coupling of the superconductors (S), magnetic impurities give rise to superimposed Yu-Shiba-Rusinov (YSR)-like states. We show that these states have genuine features, which can be tuned by changing the junction characteristics and allow to clearly identify the states in STM experiments. Particularly interesting are zero-energy YSR-like states in the center of the superconducting gap, which form for a wide range of accessible junction configurations. By calculating the Josephson current flow across the system from the spectrum, we unravel a unique connection between these zero-energy YSR-like states and the appearance of 0-π transitions in the current flow. Our findings shed new light on the physics of 0-π transitions in Josephson junctions.

This work was supported by DFG SFB Nos. 689 and 1277, by the European Union's Horizon 2020 research and innovation programme under Grant agreement No. 696656, and by the International Doctorate Program Topological Insulators of the Elite Network of Bavaria.