Microscopic Theory of Current-Spin Interaction in Ferromagnets

TL;DR

This paper develops a microscopic theoretical framework to understand how electric currents influence magnetization dynamics and vice versa in ferromagnets, focusing on spin torques and spin motive forces.

Contribution

It provides a unified microscopic theory describing both current-induced spin torques and spin motive forces in ferromagnets, emphasizing dissipative effects from spin relaxation.

Findings

Identification of dissipative spin torques from spin relaxation

Analysis of spin motive force as a reaction to spin torques

Unified description of current-magnetization interactions

Abstract

Interplay between magnetization dynamics and electric current in a conducting ferromagnet is theoretically studied based on a microscopic model calculation. First, the effects of the current on magnetization dynamics (spin torques) are studied with special attention to the "dissipative" torques arising from spin-relaxation processes of conduction electrons. Next, an analysis is given of the "spin motive force", namely, a spin-dependent 'voltage' generation due to magnetization dynamics, which is the reaction to spin torques. Finally, an attempt is presented of a unified description of these effects.