SKM 2023 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 27: Focus Session: Unconventional Transport Phenomena in Low-Dimensional Superconducting Heterostructures

TT 27.10: Vortrag

Mittwoch, 29. März 2023, 12:45–13:00, HSZ 03

Microscopic theory of gate-voltage mediated surface pair breaking and its impact on a superconducting wire — •Subrata Chakraborty, Danilo Nikolic, and Wolfgang Belzig — Fachbereich Physik, Universität Konstanz, D-78457 Konstanz, Germany

Gate-induced supercurrent suppression in a superconducting nano-bridge is a hot topic for research in present days. Recent experiments find supercurrent suppression in this nano-bridge for high gate electric fields [1-3]. The microscopic understanding of this effect is not clear till now. According to many experimental findings, there are three distinct tentative mechanisms, which could be responsible for this event, at high gate fields. In our work, we theoretically investigate the role of gate-mediated surface pair breaking on the supercurrent suppression. We show that in presence of a small concentration of magnetic impurities on the surface of the bridge, large gate-fields result in strong spin-flip scattering at the surface. Using microscopic modelling based on the quasiclassical Usadel equation we present the full phase diagram of the wire, that shows a supercurrent suppression very similar to some experiment. We speculate, that our generic theoretical predictions based on this microscopic effect can be tested experimentally by modifying the surface.

[1] G. De Simoni et al., Nat. Nanotechnol.13, 802 (2018)

[2] I. Golokolenov et al., Nat. Commun. 12, 2747 (2021)

[3] L. D. Alegria et al., Nat. Nanotechnol. 16, 404 (2021)