Controlling spin supercurrents via nonequilibrium spin injection

Jabir Ali Ouassou,Jacob Linder,Jason W A Robinson

doi:10.1038/s41598-019-48945-0

Jabir Ali Ouassou, Jacob Linder + Show 1 more

Open Access

https://doi.org/10.1038/s41598-019-48945-0

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Abstract

We propose a mechanism whereby spin supercurrents can be manipulated in superconductor/ferromagnet proximity systems via nonequilibrium spin injection. We find that if a spin supercurrent exists in equilibrium, a nonequilibrium spin accumulation will exert a torque on the spins transported by this current. This interaction causes a new spin supercurrent contribution to manifest out of equilibrium, which is proportional to and polarized perpendicularly to both the injected spins and the equilibrium spin current. This is interesting for several reasons: as a fundamental physical effect; due to possible applications as a way to control spin supercurrents; and timeliness in light of recent experiments on spin injection in proximitized superconductors.

Highlights

We propose a mechanism whereby spin supercurrents can be manipulated in superconductor/ ferromagnet proximity systems via nonequilibrium spin injection
The nonequilibrium spin accumulation ρs can be related to a spin distribution function hs
We have shown that injection of a nonequilibrium spin accumulation can be used to generate new spin supercurrent components

Summary

Introduction

We propose a mechanism whereby spin supercurrents can be manipulated in superconductor/ ferromagnet proximity systems via nonequilibrium spin injection. In the field of superconducting spintronics, a key objective is to study the interactions between superconductors (S) and ferromagnets (F)[1,2,3,4] These interactions produce new types of Cooper pairs |↑↑〉 and |↓↓〉 with a net spin polarization, enabling the use of S/F systems for dissipationless spin transport. While most work so far relies on magnetic control of spin it would be interesting to determine if a spin supercurrent can supercurrents be controlled via via rotaelectronic spin injection instead Such a mechanism might be more beneficial for coupling superconducting and nonsuperconducting spintronics devices. It has been proposed that this effect was assisted by a Cooper-pair spin supercurrent[13], alternative explanations have been proposed[24] In this manuscript, we consider how an injected nonequilibrium spin accumulation in general affects an existing spin supercurrent (see Fig. 1). These terms have a natural interpretation in the form of the injected spin accumulation a new component Jsneq ~ ρs ρs ×

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