Finite field transport response of a dilute magnetic topological insulator based Josephson junction

TL;DR

This paper reports the first observation of induced supercurrent in a magnetic topological insulator Josephson junction, revealing complex magnetoresistance effects influenced by magnetic flux focusing, without proximity-induced superconductivity.

Contribution

It demonstrates supercurrent in a magnetic topological insulator junction at low fields and clarifies magnetoresistance origins, highlighting flux focusing effects over proximity effects.

Findings

First supercurrent in magnetic topological insulator junctions

Hysteretic magnetoresistance due to flux focusing

Superconductivity effects dominated by flux focusing, not proximity

Abstract

Hybrid samples combining superconductors with magnetic topological insulators are a promising platform for exploring exotic new transport physics. We examine a Josephson junction of such a system, based on the dilute magnetic topological insulator (Hg,Mn)Te and the type II superconductor MoRe. In the zero and very low field limit, to the best of our knowledge, the device shows, for the first time, induced supercurrent through a magnetically doped semiconductor, in this case a topological insulator. At higher fields, a rich and hysteretic magnetoresistance is revealed. Careful analysis shows that the explanation of this behaviour can be found in magnetic flux focusing stemming from the Meissner effect in the superconductor, without invoking any role of proximity induced superconductivity. The phenomena is important, as it will ubiquitously co-exist with any exotic new physics that may be present in this class of devices.