Origin of Magnetic Circular Dichroism in GaMnAs: Giant Zeeman Splitting versus Spin Dependent Density of States

TL;DR

This paper explains that magnetic circular dichroism in GaMnAs mainly results from spin-dependent density of states differences caused by Mn impurities, challenging the traditional Zeeman splitting explanation.

Contribution

It provides a unified theoretical interpretation showing MCD in GaMnAs is primarily due to impurity-induced density of states differences, not Zeeman splitting.

Findings

MCD arises mainly from spin-dependent density of states differences.

Zeeman splitting plays a secondary role in MCD.

Impurity band effects are crucial in understanding MCD in GaMnAs.

Abstract

We present a unified interpretation of experimentally observed magnetic circular dichroism (MCD) in the ferromagnetic semiconductor (Ga,Mn)As, based on theoretical arguments, which demonstrates that MCD in this material arises primarily from a difference in the density of spin-up and spin-down states in the valence band brought about by the presence of the Mn impurity band, rather than being primarily due to the Zeeman splitting of electronic states.