Magnetoanisotropic Josephson effect due to interfacial spin-orbit fields in superconductor/ferromagnet/superconductor junctions

TL;DR

This paper theoretically investigates how interfacial spin-orbit coupling influences the Josephson current in superconductor/ferromagnet/superconductor junctions, revealing giant magnetoanisotropies and controllable 0-$ extpi$ transitions.

Contribution

It introduces a detailed theoretical model showing how interfacial Rashba and Dresselhaus spin-orbit couplings cause giant magnetoanisotropies and enable control of Josephson current directions.

Findings

Giant magnetoanisotropies in Josephson current due to spin-orbit coupling.

Control of 0-$ extpi$ transitions via spin-orbit strength and magnetization orientation.

Significant anisotropies near 0-$ extpi$ transition points.

Abstract

We study theoretically the effects of interfacial Rashba and Dresselhaus spin-orbit coupling in superconductor/ferromagnet/superconductor (S/F/S) Josephson junctions---with allowing for tunneling barriers between the layers---by solving the Bogoljubov-de Gennes equation for a realistic heterostructure and applying the Furusaki-Tsukada technique to calculate the electric current at a finite temperature. The presence of spin-orbit couplings leads to out- and in-plane magnetoanisotropies of the Josephson current, which are giant in comparison to current magnetoanisotropies in similar normal-state ferromagnet/normal metal (F/N) junctions. Especially huge anisotropies appear in the vicinity of $ 0 $-$ \pi $ transitions, caused by the exchange-split bands in the ferromagnetic metal layer. We also show that the direction of the Josephson critical current can be controlled (inducing $ 0 $-$ \pi $ transitions) by the strength of the spin-orbit coupling and, more crucial, by the orientation of the magnetization. Such a control can bring new functionalities into Josephson junction devices.