Modification of the Landau-Lifshitz Equation in the Presence of a Spin-Polarized Current in CMR and GMR Materials

摘要

We derive a continuum equation for the magnetization of a conductingferromagnet in the presence of a spin-polarized current. Current effects enterin the form of a topological term in the Landau-Lifshitz equation . In thestationary situation the problem maps onto the motion of a classical chargedparticle in the field of a magnetic monopole. The spatial dependence of themagnetization is calculated for a one-dimensional geometry and suggestions forexperimental observation are made. We also consider time-dependent solutionsand predict a spin-wave instability for large currents.