Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

TT: Fachverband Tiefe Temperaturen

TT 89: Focus Session: Evolution of Topological Materials into Superconducting Nanodevices (joint session HL/TT)

TT 89.6: Hauptvortrag

Freitag, 22. März 2024, 12:15–12:45, EW 202

Exploring Josephson Junctions made of Topological Insulator Wires and Superconductors — •Dieter Weiss — Experimentelle und Angewandte Physik, Universität Regensburg, 93040 Regensburg

Topological insulator (TI) nanowires in proximity to conventional superconductors provide a tunable platform to realize topological superconductivity and Majorana bound states (MBS) [1]. Tuning is achieved by an axial magnetic flux φ which transforms the system from trivial at φ=0 to topologically non-trivial when a magnetic flux quantum φ₀=h/2e threads the wire cross section. Here we study the supercurrent I_C and its periodicity on the superconducting phase as a function of the axial magnetic field using Josephson junctions made of strained HgTe wires (the TI) with Nb contacts. Depending on the transparency of the contacts we observe either a monotonically decreasing I_C with increasing B for high transparency or h/2e, h/4e, and even h/8e periodic oscillations of the supercurrent for samples with lower transparency [2]. Samples with high transparency exhibit 4π periodic supercurrents, a signature of MBS [3]. I will discuss the significance of these signatures and the origin of the flux-periodic oscillations.

Work done in collaboration with Ralf Fischer, Wolfgang Himmler, Jordi Picó-Cortés, Jacob Fuchs, Michael Barth, Cosimo Gorini, Klaus Richter, Gloria Platero, Milena Grifoni, Dmitriy A. Kozlov, Nikolay N. Mikhailov, Sergey A. Dvoretsky, and Christoph Strunk.

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

[2] W. Himmler et al., Phys. Rev. Res. 5, 043021 (2023)

[3] R. Fischer et al., Phys. Rev. Res. 4, 013087 (2022)

Keywords: topological insulator; HgTe; wires; Josephson junction; Majorana bound states