Microscopic mechanism of the non-crystalline anisotropic magnetoresistance in (Ga,Mn)As

TL;DR

This paper develops a microscopic model to explain the anisotropic magnetoresistance in (Ga,Mn)As, highlighting the role of magnetic Mn scattering and spin-orbit interaction, and provides an analytical model matching experimental sign predictions.

Contribution

It introduces a simple analytical model based on heavy-hole bands and impurity scattering that captures the dominant AMR mechanism in (Ga,Mn)As.

Findings

The model predicts the correct sign of AMR.

Magnetic Mn scattering combined with spin-orbit interaction is the dominant mechanism.

Destructive interference between electric and magnetic scattering causes the observed AMR behavior.

Abstract

Starting with a microscopic model based on the Kohn-Luttinger Hamiltonian and kinetic p-d exchange combined with Boltzmann formula for conductivity we identify the scattering from magnetic Mn combined with the strong spin-orbit interaction of the GaAs valence band as the dominant mechanism of the anisotropic magnetoresistance (AMR) in (Ga,Mn)As. This fact allows to construct a simple analytical model of the AMR consisting of two heavy-hole bands whose charge carriers are scattered on the impurity potential of the Mn atoms. The model predicts the correct sign of the AMR (resistivity parallel to magnetization is smaller than perpendicular to magnetization) and identifies its origin arising from the destructive interference between electric and magnetic part of the scattering potential of magnetic ionized Mn acceptors when the carriers move parallel to the magnetization.