Magnetization Dissipation in the Ferromagnetic Semiconductor (Ga,Mn)As
  We compute the Gilbert damping in (Ga,Mn)As based on the scattering theory of magnetization relaxation. The disorder scattering is included non-perturbatively. In the clean limit, the spin-pumping from the localized d-electrons to the itinerant holes dominates the relaxation processes. In the diffusive regime, the breathing Fermi-surface effect is balanced by the effects of interband scattering, which cause the Gilbert damping constant to saturate at around 0.005. In small samples, the system shape induces a large anisotropy in the Gilbert damping. 
Kjetil M.D. Hals and Arne Brataas
cond-mat.mtrl-sci cond-mat.mes-hall