Hallmarks of non-trivial topology in Josephson junctions based on oxide nanochannels

TL;DR

This paper demonstrates that oxide-based Josephson junctions with Rashba spin-orbit coupling exhibit signatures of topological superconductivity, including Majorana bound states, through anomalous critical current behavior and current-phase relation features.

Contribution

It provides the first microscopic analysis linking topological superconductivity signatures to oxide interface Josephson junctions with Rashba spin-orbit interaction.

Findings

Critical current enhancement at small magnetic fields indicates non-trivial topology.

Presence of Majorana bound states at the edges of superconducting leads.

Sawtooth profile in the current-phase relation as a topological signature.

Abstract

We investigate the topological properties of a Josephson junction obtained by constraining a two-dimensional electron gas at oxide interface to form a quasi-1D conductor. We reveal an anomalous critical current behaviour with a magnetic field applied perpendicular to the Rashba spin-orbit one. We relate the observed critical current enhancement at small magnetic fields with a non-trivial topology, accompanied by Majorana bound states (MBSs) pinned at the edges of the superconducting leads. Signatures of MBSs also include a sawtooth profile in the current-phase relation. Our findings allow to recognize fingerprints of topological superconductivity in non-centrosymmetric materials and confined systems with Rashba spin-orbit interaction, and to explain recent experimental observations for which a microscopic description is still lacking.