Roles of nonequilibrium conduction electrons on the magnetization dynamics of ferromagnets

The mutual dependence of spin-dependent conduction and magnetization dynamics of ferromagnets were studied in order to provide the key mechanisms in various spin-dependent phenomena. The response of the conduction electron spins in a spatial and time varying magnetization were computed in the time-dependent semiclassical transport theory. The induced nonequilibrium conduction spin density was shown to generate four spin torques acting on the magnetization, with each torque playing a different role in magnetization dynamics. It was also found that one of these torques is crucial for the interpretetion of experimental data on domain wall motion.