Strain, magnetic anisotropy, and anisotropic magnetoresistance in (Ga,Mn)As on high-index substrates: application to (113)A-oriented layers

TL;DR

This paper presents a theoretical framework for calculating strain, magnetic anisotropy, and anisotropic magnetoresistance in (Ga,Mn)As layers on high-index substrates, validated through experimental measurements on (113)A-oriented layers.

Contribution

It introduces analytical expressions linking lattice distortion, magnetic anisotropy, and magnetoresistance for high-index (Ga,Mn)As layers, combining theory with experimental validation.

Findings

Strain tensor and shear angle determined by x-ray diffraction.

Magnetotransport measurements reveal field-dependent resistivity parameters.

Theoretical expressions accurately describe magnetic and transport properties.

Abstract

Based on a detailed theoretical examination of the lattice distortion in high-index epilayers in terms of continuum mechanics, expressions are deduced that allow the calculation and experimental determination of the strain tensor for (hhl)-oriented (Ga,Mn)As layers. Analytical expressions are derived for the strain-dependent free-energy density and for the resistivity tensor for monoclinic and orthorhombic crystal symmetry, phenomenologically describing the magnetic anisotropy (MA) and anisotropic magnetoresistance (AMR) by appropriate anisotropy and resistivity parameters, respectively. Applying the results to (113)A orientation with monoclinic crystal symmetry, the expressions are used to determine the strain tensor and the shear angle of a series of (113)A-oriented (Ga,Mn)As layers by high-resolution x-ray diffraction and to probe the MA and AMR at 4.2 K by means of angle-dependent magnetotransport. Whereas the transverse resistivity parameters are nearly unaffected by the magnetic field, the parameters describing the longitudinal resistivity are strongly field dependent.