Local lattice distortions around $\rm{Mn^{2+}}$ cause in-plane uniaxial magnetic anisotropy in Ga(Mn)As

TL;DR

This paper demonstrates how local lattice distortions around Mn²⁺ impurities induce in-plane uniaxial magnetic anisotropy in Ga(Mn)As by breaking tetrahedral symmetry and stabilizing magnetization directions, explaining experimental observations.

Contribution

It reveals the role of local lattice distortions and strain in breaking symmetry and controlling magnetic anisotropy in Ga(Mn)As, providing a theoretical explanation for experimental findings.

Findings

Local lattice distortions break tetrahedral symmetry.

Distortions and strain stabilize magnetization along <110> directions.

The mechanism explains observed in-plane uniaxial magnetic anisotropy.

Abstract

We theoretically investigate the interplay between local lattice distortions around $\rm{Mn^{2+}}$ ion impurity and the ion's magnetic polarization, mediated through spin-orbit coupling of hole. We show that the tetrahedral symmetry around $\rm{Mn^{2+}}$ ion impurity is spontaneously broken even in the paramagnetic regime. Modest local lattice distortions around the impurity $\rm{Mn^{2+}}$ ion, along with the growth strain, stabilize magnetization along $< 110 >$ directions, in the ferromagnetic regime. We explain the experimentally observed in-plane uniaxial magnetic anisotropy seen in this system using this symmetry-breaking mechanism.