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TT: Fachverband Tiefe Temperaturen

TT 16: Poster: Transport

TT 16.19: Poster

Monday, March 27, 2023, 15:00–18:00, P2/OG4

Topological insulator as barrier in Josephson junction — •Anton Montag, Alexander Ziesen, and Fabian Hassler — RWTH Aachen University, Aachen, Germany

We numerically study the behavior of a long Josephson junction in a superconductor-topological insulator-superconductor setup. An s-wave superconductor is deposited on the disordered surface of a three-dimensional topological insulator proximitizing the surface states on both sides of the junction. The normal region is probed by a local tunnelling contact. We simulate the tunnel spectrum at energies below the bulk gap of the topological insulator as a function of the phase difference of the superconducting order parameter across the junction. The low-energy spectrum can be divided into trivial Andreev bound states usually appearing at higher energies and chiral edge modes which become gapless at a phase difference of π. Since the latter are topologically protected, they are essentially not affected by symmetry preserving onsite potential disorder on the topological insulator surface. We show the simulated tunnel spectra for various disorder configurations and compare it to analytical calculations.