$4\pi$-periodic supercurrent tuned by an axial magnetic flux in topological insulator nanowires

Ralf Fischer; Jordi Picó-Cortés; Wolfgang Himmler; Gloria Platero; Milena Grifoni; Dmitriy A. Kozlov; N. N. Mikhailov; Sergey A. Dvoretsky; Christoph Strunk; Dieter Weiss

arXiv · 2110.05143

$4\pi$-periodic supercurrent tuned by an axial magnetic flux in topological insulator nanowires

Ralf Fischer·Jordi Picó-Cortés·Wolfgang Himmler·Gloria Platero·Milena Grifoni·Dmitriy A. Kozlov·N. N. Mikhailov·Sergey A. Dvoretsky·Christoph Strunk·Dieter Weiss

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Abstract

Topological insulator (TI) nanowires in proximity with conventional superconductors have been proposed as a tunable platform to realize topological superconductivity and Majorana zero modes (MZM). The tuning is done using an axial magnetic flux $\Phi$ which allows transforming the system from trivial at $\Phi=0$ to topologically nontrivial when half a magnetic flux quantum $\Phi_0/2$ threads the wire's cross-section. Here we explore the expected topological transition in TI-wire-based Josephson junctions as a function of magnetic flux by probing the $4\pi$-periodic fraction of the supercurrent, which is considered as an indicator of topological superconductivity. Our data suggest that this $4\pi$-periodic supercurrent is at lower magnetic field largely of trivial origin, but that at magnetic fields above $\sim\Phi_{0}/4$ topological $4\pi$-periodic supercurrents take over.

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Ralf Fischer, Jordi Picó-Cortés, Wolfgang Himmler, Gloria Platero, Milena Grifoni, Dmitriy A. Kozlov, N. N. Mikhailov, Sergey A. Dvoretsky, Christoph Strunk, Dieter Weiss. 2021-10-11. $4\pi$-periodic supercurrent tuned by an axial magnetic flux in topological insulator nanowires. https://arxiv.org/abs/2110.05143

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