Detection of stacking faults breaking the [110]/[1-10] symmetry in ferromagnetic semiconductors (Ga,Mn)As and (Ga,Mn)(As,P)

TL;DR

This study reveals that stacking faults in (Ga,Mn)As and (Ga,Mn)(As,P) induce a symmetry breaking mechanism that explains the observed in-plane uniaxial magnetocrystalline anisotropy, supported by high-resolution x-ray diffraction and density functional calculations.

Contribution

It demonstrates that stacking faults cause [110]/[1-10] symmetry breaking, influencing magnetic anisotropy in ferromagnetic semiconductors, a novel insight into their structural-magnetic relationship.

Findings

Stacking faults are present in specific crystallographic planes.

Mn impurities are attracted to stacking faults.

The symmetry breaking explains magnetic anisotropy.

Abstract

We report high resolution x-ray diffraction measurements of (Ga,Mn)As and (Ga,Mn)(As,P) epilayers. We observe a structural anisotropy in the form of stacking faults which are present in the (111) and (11-1) planes and absent in the (-111) and (1-11) planes. The stacking faults produce no macroscopic strain. They occupy 0.01 - 0.1 per cent of the epilayer volume. Full-potential density functional calculations evidence an attraction of Mn_Ga impurities to the stacking faults. We argue that the enhanced Mn density along the common [1-10] direction of the stacking fault planes produces sufficiently strong [110]/[1-10] symmetry breaking mechanism to account for the in-plane uniaxial magnetocrystalline anisotropy of these ferromagnetic semiconductors.