Magnetization Dissipation in the Ferromagnetic Semiconductor (Ga,Mn)As

TL;DR

This paper calculates the Gilbert damping in (Ga,Mn)As using scattering theory, revealing how disorder and sample shape influence magnetization relaxation, with implications for spintronic device design.

Contribution

It provides a non-perturbative calculation of Gilbert damping in (Ga,Mn)As, highlighting the roles of disorder, spin-pumping, and sample shape effects.

Findings

Gilbert damping saturates at ~0.005 in the diffusive regime.

Disorder scattering significantly affects relaxation.

Sample shape induces anisotropy in damping.

Abstract

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.