Strain dependence of the Mn anisotropy in ferromagnetic semiconductors observed by x-ray magnetic circular dichroism

TL;DR

This study uses x-ray magnetic circular dichroism to reveal how strain influences the magnetic anisotropy of Mn in ferromagnetic semiconductors, showing that strain reversal affects the uniaxial anisotropy and hole character.

Contribution

It demonstrates the strain dependence of Mn anisotropy in ferromagnetic semiconductors using XMCD, highlighting the relationship between strain, spectral features, and hole character.

Findings

Reversing strain reverses the uniaxial anisotropy sign.

Spectral shape depends on magnetization orientation.

Hole character increases with carrier localization.

Abstract

We demonstrate sensitivity of the Mn 3d valence states to strain in the ferromagnetic semiconductors (Ga,Mn)As and (Al,Ga,Mn)As, using x-ray magnetic circular dichroism (XMCD). The spectral shape of the Mn $L_{2,3}$ XMCD is dependent on the orientation of the magnetization, and features with cubic and uniaxial dependence are distinguished. Reversing the strain reverses the sign of the uniaxial anisotropy of the Mn $L_3$ pre-peak which is ascribed to transitions from the Mn 2p core level to p-d hybridized valence band hole states. With increasing carrier localization, the $L_3$ pre-peak intensity increases, indicating an increasing 3d character of the hybridized holes.