Spin torque due to diffusive spin current in magnetic texture

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.