Direct coupling between magnetism and superconducting current in Josephson Phi junction

TL;DR

This paper demonstrates that a Josephson Phi junction, involving a superconductor and a magnetic metal with spin-orbit interaction, exhibits a finite phase difference directly coupling superconducting current and magnetism, advancing superconducting spintronics.

Contribution

It introduces a mechanism for Phi junction formation that directly couples superconducting current with magnetic moments via spin-orbit interaction.

Findings

The current-phase relation is non-sinusoidal in such junctions.

The ground state phase difference Phi depends on spin-orbit strength and exchange field.

This mechanism enables direct magnetic-superconducting current coupling.

Abstract

We study the proximity effect between conventional superconductor and magnetic normal metal with a spin-orbit interaction of the Rashba type. Using the phenomenological Ginzburg-Landau theory and the quasiclassical Eilenberger approach it is demonstrated that the Josephson junction with such a metal as a weak link has a special non-sinusoidal current-phase relation. The ground state of this junction is caracterized by the finite phase difference Phi, which is proportional to the strength of the spin-orbit interaction and the exchange field in the normal metal. The proposed mechanism of the Phi junction formation gives a direct coupling between the superconducting current and the magnetic moment in the weak link. Therefore the Phi junctions open interesting perspectives for the superconducting spintronics.