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TT: Fachverband Tiefe Temperaturen

TT 66: Superconductivity: Yu-Shiba-Rusinov and Andreev Physics

TT 66.6: Talk

Thursday, March 21, 2024, 10:45–11:00, H 3005

Full counting statistics of Yu-Shiba-Rusinov bound states — •David Christian Ohnmacht¹, Wolfgang Belzig¹, and Juan Carlos Cuevas² — ¹Fachbereich Physik, Universität Konstanz, D-78457 Konstanz, Germany — ²Departamento de Física Teórica de la Materia Condensada and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, E-28049 Madrid, Spain

We adapt the concept of full counting statistics (FCS) to provide the deepest insight thus far into the spin-dependent transport in systems containing Yu-Shiba-Rusinov (YSR) states [1]. Such systems include single-impurity junctions with a normal and a superconducting (SC) STM tip, as well as double-impurity systems [2]. The FCS concept allows us to identify every tunneling process that plays a role in these situations and to classify them according to the charge transferred in them. In particular, our approach is able to reproduce the experimental results recently reported on the shot noise of a single-impurity junction with a normal STM tip [3]. We also predict the signatures of resonant multiple Andreev reflections in the shot noise of single-impurity junctions with two SC electrodes and show that the FCS approach allows us to understand conductance features that have been incorrectly interpreted in the literature. In the case of double-impurity junctions we show that the direct tunneling between YSR states is characterized by a strong reduction of the Fano factor that reaches a minimum value of 7/32.

[1] D. C. Ohnmacht et. al., Phys. Rev. Res. 5 (2023) 033176

[2] H. Huang et. al., Nat. Phys. 16 (2020) 1227

[3] U. Thupakula et. al., Phys. Rev. Lett. 128 (2022) 247001

Keywords: Superconductivity; Yu-Shiba-Rusinov states; Andreev reflection; Spintronics; Full counting statistics