Influence of a uniform current on collective magnetization dynamics in a ferromagnetic metal -: art. no. 174412

We discuss the influence of a uniform current j on the magnetization dynamics of a ferromagnetic metal. We find that the magnon energy epsilon((q) over right arrow) has a current-induced contribution proportional to (q) over right arrow.(J) over right arrow, where (J) over right arrow is the spin current, and predict that collective dynamics will be more strongly damped at finite (j) over right arrow. We obtain similar results for models with and without local moment participation in the magnetic order. For transition metal ferromagnets, we estimate that the uniform magnetic state will be destabilized for jgreater than or similar to10(9) A cm(-2). We discuss the relationship of this effect to the spin-torque effects that alter magnetization dynamics in inhomogeneous magnetic systems.