Inversion symmetry of Josephson current as test of chiral domain wall motion in Sr$_{2}$RuO$_{4}$

TL;DR

This study investigates the inversion symmetry of Josephson current in Nb/Sr$_{2}$RuO$_{4}$ junctions to infer the size and behavior of chiral domains, revealing domain wall dynamics through critical current measurements.

Contribution

It demonstrates that reducing junction size suppresses domain wall effects, allowing estimation of chiral domain size in Sr$_{2}$RuO$_{4}$ using Josephson junction measurements.

Findings

Inversion symmetry of $I_c(H)$ recovers at micron-scale junctions.

Chiral domain size estimated at approximately several microns.

Disappearance of domain walls correlates with symmetry restoration.

Abstract

Clarifying the chiral domains structure of superconducting Sr$_{2}$RuO$_{4}$ has been a long-standing issue in identifying its peculiar topological superconducting state. We evaluated the critical current $I_{c}$ versus the magnetic field $H$ of Nb/Sr$_{2}$RuO$_{4}$ Josephson junctions, changing the junction dimension in expectation of that the number of domains in the junction is controlled. $I_{c}(H)$ exhibits a recovery from inversion symmetry breaking to invariance when the dimension is reduced to several microns. This inversion invariant behavior indicates the disappearance of domain walls; thus, the size of a single domain is estimated at approximately several microns.