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HL: Fachverband Halbleiterphysik

HL 31: Focus Session: Evolution of Topological Materials into Superconducting Nanodevices II (joint session HL/TT)

HL 31.4: Talk

Wednesday, March 20, 2024, 12:30–12:45, EW 202

Superconducting diode effect in topological insulator nanowire Josephson junctions — •Ella N. Nikodem, Jakob Schluck, Mahasweta Bagchi, Zhiwei Wang, and Yoichi Ando — Physics Institute II, University of Cologne, Zülpicher Straße 77, 50937 Köln, Germany

Topological insulator nanowires coupled to conventional superconductors were predicted to host Majorana zero modes more than a decade ago [1]. An indication of the presence of such Majorana bound states in Josephson junction devices based on these nanowires is an enhanced superconducting diode effect in the topological regime, attributed to their 4π-periodic contribution to the current phase relation [2]. In this talk, we report our investigations of the superconducting diode effect in side-contacted etched nanowires made from exfoliated flakes of the bulk-insulating topological insulator BiSbTeSe2. We observed a strong dependence of the critical current on gate voltage and the magnetic field along the nanowire, as well as a significant superconducting diode effect. Its direction and magnitude can be switched by tuning the aforementioned parameters. Possible relevance of the Majorana bound states in the observed diode effect will be discussed.

[1] A. Cook and M. Franz, Phys. Rev. B 84, 201105(R) (2011).

[2] H. F. Legg et al., arXiv:2301.13740 (2023).

Keywords: Superconductivity; Topological matter; Low temperature