Comparison of Origins of Re-Entrant Supercurrents at High In-Plane Magnetic Fields in Planar InAs-Al Josephson Junctions

TL;DR

This study investigates re-entrant supercurrents in InAs-Al Josephson junctions under high magnetic fields, exploring their origins as either topological transitions or disorder-induced interference effects.

Contribution

The paper provides experimental data on re-entrant supercurrents and demonstrates through simulations that these can arise from mode interference without topological effects.

Findings

Re-entrant switching currents observed in high in-plane magnetic fields.

Some re-entrances align with topological or 0-$ ext{pi}$ transition signatures.

Simulations show disorder-induced interference can mimic topological signatures.

Abstract

Hybrid superconductor-semiconductor systems with large spin-orbit coupling are important platforms for realizing topological or triplet superconductivity. Planar Josephson junctions made using these materials are predicted to enter the topological state by tuning the phase difference between the two superconductors from 0 to $\pi$. The 0-$\pi$ transition can be driven by magnetic field through Zeeman splitting of subbands in the semiconductor. It is expected to manifest as a node, or a re-entrance, in the critical current. Here we present re-entrant switching currents from several InAs/Al planar Josephson junctions in high in-plane magnetic fields. We find that re-entrances in some devices conform with expected signatures for topological or 0-$\pi$ transitions. However, we show that the data can also be explained in terms of mode interference in the junction in the presence of disorder. We also present simulations of supercurrent interference under in-plane fields that can reproduce re-entrances due to corrugated weak link without invoking the Zeeman effect or topology.