Detecting Perfect Transmission in Josephson Junctions on the Surface of Three Dimensional Topological Insulators

TL;DR

This paper investigates Josephson junctions on 3D topological insulator nanowires, revealing signatures of perfect transmission and Majorana fermions through flux-dependent critical current peaks, robust against disorder and temperature.

Contribution

It demonstrates the presence of perfect transmission modes supporting Majorana fermions in topological insulator nanowire Josephson junctions under magnetic flux.

Findings

Peak in critical current at flux h/2e indicates perfect transmission.

Peak persists with disorder and finite temperature, showing robustness.

Signatures are observable in current-phase relation and flux dependence.

Abstract

We consider Josephson junctions on surfaces of three dimensional topological insulator nanowires. We find that in the presence of a parallel magnetic field, short junctions on nanowires show signatures of a perfectly transmitted mode capable of supporting Majorana fermions. Such signatures appear in the current-phase relation in the presence or absence of the fermion parity anomaly, and are most striking when considering the critical current as a function of flux \Phi, which exhibits a peak at \Phi=h/2e. The peak sharpens in the presence of disorder at low but finite chemical potentials, and can be easily disentangled from weak-antilocalization effects. The peak also survives at small but finite temperatures, and represents a realistic and robust hallmark for perfect transmission and the emergence of Majorana physics inside the wire.