Anisotropic Magnetoresistance components in (Ga,Mn)As

TL;DR

This study combines experimental and theoretical approaches to analyze the anisotropic magnetoresistance in (Ga,Mn)As, revealing how different components depend on spin-orbit coupling, impurity potentials, and strain effects, with implications for magnetic materials.

Contribution

It provides a detailed analysis of the non-crystalline and crystalline AMR components in (Ga,Mn)As, including experimental methods and theoretical insights into their physical origins and control mechanisms.

Findings

Non-crystalline AMR sign depends on spin-orbit coupling and impurity potential.

Crystalline AMR is associated with valence band warping.

AMR can be tuned by local strain relaxation.

Abstract

Our experimental and theoretical study of the non-crystalline and crystalline components of the anisotropic magnetoresistance (AMR) in (Ga,Mn)As is aimed at exploring the basic physical aspects of this relativistic transport effect. The non-crystalline AMR reflects anisotropic lifetimes of the holes due to polarized Mn impurities while the crystalline AMR is associated with valence band warping. We find that the sign of the non-crystalline AMR is determined by the form of spin-orbit coupling in the host band and by the relative strengths of the non-magnetic and magnetic contributions to the impurity potential. We develop experimental methods directly yielding the non-crystalline and crystalline AMR components which are then independently analyzed. We report the observation of an AMR dominated by a large uniaxial crystalline component and show that AMR can be modified by local strain relaxation. We discuss generic implications of our experimental and theoretical findings including predictions for non-crystalline AMR sign reversals in dilute moment systems.