Scattering theory of charge-current–induced magnetization dynamics

¹  Department of Physics, Norwegian University of Science and Technology - NO-7491, Trondheim, Norway
²  Department of Physics and Astronomy, University of California - Los Angeles, CA 90095, USA

Corresponding author: kjetil.hals@ntnu.no

Received: 12 January 2010
Accepted: 4 May 2010

Abstract

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 × 10⁶ A/cm². Our results are in agreement with a recent experimental observation of charge-current–induced magnetization switching in (Ga, Mn)As.