Valence band orbital polarization in III-V ferromagnetic semiconductors

TL;DR

This study uses x-ray magnetic circular dichroism to measure valence band orbital magnetic moments in (III,Mn)As ferromagnetic semiconductors, revealing element-specific orbital polarization and strain effects on magnetic anisotropy.

Contribution

It provides the first direct measurement of valence band orbital magnetic moments in (III,Mn)As using XMCD, highlighting the role of strain and element-specific contributions.

Findings

As 4p orbital magnetic moment is about -0.1 μB per hole.

Strain significantly influences the orbital magnetic moment and magnetic anisotropy.

Mn and As K edge signals both have positive signs, indicating Mn 4p states contribute to spectra.

Abstract

The element-specific technique of x-ray magnetic circular dichroism (XMCD) is used to directly determine the magnitude and character of the valence band orbital magnetic moments in (III,Mn)As ferromagnetic semiconductors. A distinct dichroism is observed at the As K absorption edge, yielding an As 4p orbital magnetic moment of around -0.1 Bohr magnetons per valence band hole. This is strongly influenced by strain, indicating its crucial influence on the magnetic anisotropy. The dichroism at the Ga K edge is much weaker. The K edge XMCD signals for Mn and As both have positive sign, which indicates the important contribution of Mn 4p states to the Mn K edge spectra.