Josephson current in s-wave superconductor / Sr_2RuO_4 junctions

TL;DR

This paper theoretically investigates the Josephson effect between s-wave and Sr$_2$RuO$_4$ superconductors, revealing how spin-orbit scattering influences the current-phase relationship due to SRO's chiral pairing symmetry.

Contribution

It demonstrates the impact of spin-orbit scattering on Josephson current components in s-wave/SRO junctions, highlighting the role of chiral pairing symmetry.

Findings

Josephson current is mainly proportional to sin 2φ without spin-flip scattering.

Spin-orbit scattering introduces a cos φ component to the Josephson current.

The results connect the current-phase relation to the chiral pairing symmetry of SRO.

Abstract

The Josephson current between an s-wave and a spin-triplet superconductor Sr$_2$RuO$_4$ (SRO) is studied theoretically. In spin-singlet / spin-triplet superconductor junctions, there is no Josephson current proportional to $\sin \phi$ in the absence of the spin-flip scattering near junction interfaces, where $\phi$ is a phase-difference across junctions. Thus a dominant term of the Josephson current is proportional to $\sin 2\phi$ . The spin-orbit scattering at the interfaces gives rise to the Josephson current proportional to $\cos\phi$, which is a direct consequence of the chiral paring symmetry in SRO.