Scattering theory of charge-current–induced magnetization dynamics

In ferromagnets, charge currents can excite magnons via the spin-orbit coupling. We develop a novel and general scattering theory of charge-current–induced macrospin magnetization torques in normal metal|ferromagnet|normal metal layers. We apply the formalism to a dirty GaAs|(Ga,Mn)As|GaAs system. By computing the charge-current–induced magnetization torques and solving the Landau-Lifshitz-Gilbert equation, we find magnetization switching for current densities as low as 5×10 6 A/cm 2 . Our results are in agreement with a recent experimental observation of charge-current–induced magnetization switching in (Ga, Mn)As.