Josephson phase shift and diode effect due to the inverse spin Hall effect

TL;DR

This paper theoretically explores how spin-orbit interaction in superconductor-normal metal-superconductor junctions causes a Josephson phase shift and diode effect via the inverse spin Hall effect, without needing broken inversion symmetry.

Contribution

It introduces a novel mechanism for the inverse spin Hall effect and diode behavior in symmetric systems, expanding understanding of spintronics in superconducting structures.

Findings

Supercurrent induces a spin Hall effect with opposite edge polarizations.

A static magnetic field causes an anomalous phase shift leading to diode behavior.

The mechanism does not require broken structural inversion symmetry.

Abstract

We theoretically study the direct and inverse spin Hall effects in a superconductor-normal metal-superconductor junction induced by a spin-orbit interaction that is invariant under spatial inversion. We show that a supercurrent induces a spin Hall effect, leading to a static spin accumulation with opposite polarizations at the two edges, analogous to that in normal conductors. For the inverse effect, we consider a spatially inhomogeneous static magnetic field and show that it induces an anomalous phase shift, which, in the presence of higher harmonics, results in a diode effect. Unlike Rashba systems, the present mechanism does not require broken structural inversion symmetry.