Probing disorder-induced time-reversal symmetry breaking in Josephson junctions

TL;DR

This study investigates how nonmagnetic disorder in superconductors can induce time-reversal symmetry breaking, using Josephson junctions with Sr2RuO4 and aluminum to detect disorder-driven TRS breaking effects through magnetoresistive hysteresis.

Contribution

It provides experimental evidence of disorder-induced TRS breaking in superconductors and introduces a physical framework based on multiband Ginzburg-Landau theory to explain these effects.

Findings

Persistent magnetoresistive hysteresis indicates TRS breaking.

Disorder induces anomalous flux detectable by aluminum.

Results align with a multiband Ginzburg-Landau model.

Abstract

The relation between superconductivity and time-reversal symmetry (TRS) is one of the most fascinating problems in condensed matter physics. Although most superconductors inherently possess TRS, nonmagnetic disorder can induce states that demonstrate the breaking of this symmetry. Yet, the identification of experimental signatures of superconductivity with broken TRS remains a challenge. Here, we fabricate vertical Josephson junctions using metallic superconductor (Al) and ion bombarded Sr2RuO4 to study disorder-driven TRS breaking effects. We observe persistent magnetoresistive hysteresis behavior dependent on the disorder deposition time that provides evidence of TRS breaking below the superconducting transition temperature. Field and temperature dependent measurements suggest that the observed effects arise from disorder-induced anomalous flux in Sr2RuO4 which can be sensitively detected by superconducting Al. Our experimental results can be accounted within a physical framework of disorder-induced reconstruction of the superconducting order parameter as described within a multiband Ginzburg-Landau approach.