Berlin 2024 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 76: Superconductivity: Tunnelling and Josephson Junctions II
TT 76.10: Vortrag
Donnerstag, 21. März 2024, 17:30–17:45, H 3010
Evidence for multiple Andreev reflection (MAR) in a hybrid superconducting single-electron transistor — •Jens Siewert1,2, Laura Sobral Rey3, David C. Ohnmacht3, Clemens B. Winkelmann4, Wolfgang Belzig3, and Elke Scheer3 — 1University of the Basque Country, 48080 Bilbao, Spain — 2Ikerbasque, 48009 Bilbao, Spain — 3University of Konstanz, 78457 Konstanz, Germany — 4Université Grenoble Alpes & CNRS, 38000 Grenoble, France
MAR and Coulomb blockade (CB) are competing phenomena in superconducting single-electron transistors: While MAR tends to significantly change the number of island excess charges, CB excludes such processes at small bias voltages. Despite substantial experimental effort over the years, up to now no unambiguous evidence for MAR processes in superconducting CB devices has been reported. To study this problem we have experimentally investigated a novel device, a single-electron transistor with one superconductor-superconductor (S-S) junction and a superconductor-normal (S-N) junction [1]. The realization of the S-S junction is chosen as a mechanically controllable break junction, such that different conductance regimes and coupling strengths can be studied in the same device. We find clear evidence for the presence of MAR processes in the current-voltage characteristics of our SSN single-electron transistor, both in the subgab region as well as for bias voltages where single-quasiparticle tunneling is possible and MAR is suppressed in single junctions.
[1] L. Sobral Rey et al., Phys. Rev. Lett. 132, 057001 (2024)
Keywords: Mechanically controllable break junction; Coulomb blockade; Multiple Andreev reflection