Spin torque due to diffusive spin current in magnetic texture

TL;DR

This paper develops a microscopic theory for spin torque caused by diffusive spin currents from spin accumulation, extending existing models and analyzing domain wall motion in nonlocal spin injection systems.

Contribution

It introduces a natural extension of spin torque theory to include diffusive spin currents and explores their effects on magnetic textures.

Findings

Derived a new expression for spin torque due to diffusive spin currents.

Applied the theory to domain wall motion in nonlocal spin injection systems.

Evaluated the torque and force exerted by diffusive spin currents on magnetic textures.

Abstract

We present a microscopic theory of spin torque due to diffusive spin currents induced by spin accumulation. The obtained expression is a natural extension of the existing one due to 'local' spin currents associated with ordinary electric currents, and is the reciprocal of the spin motive force which induces charge accumulation as studied recently [J. Shibata and H. Kohno, Phys. Rev. B84, 184408 (2011)]. The result is applied to a domain wall motion in a nonlocal spin injection system, and the torque and force due to diffusive spin current are evaluated.