Optical properties of metallic (III,Mn)V ferromagnetic semiconductors in the infrared to visible range

TL;DR

This study investigates the infrared to visible optical and magneto-optical properties of metallic (III,Mn)V ferromagnetic semiconductors using advanced band models and the Kubo formalism, revealing new features related to impurity-induced states.

Contribution

It introduces a comprehensive theoretical analysis with multi-band models and perturbative disorder treatment to explain optical phenomena in (III,Mn)V semiconductors.

Findings

Qualitative agreement with optical absorption experiments

Prediction of new features in Kerr angle and magnetic circular dichroism

Identification of impurity-induced mid-gap states effects

Abstract

We report on a study of the ac conductivity and magneto-optical properties of metallic ferromagnetic (III,Mn)V semiconductors in the infrared to visible spectrum. Our analysis is based on the successful kinetic exchange model for (III,Mn)V ferromagnetic semiconductors. We perform the calculations within the Kubo formalism and treat the disorder effects pertubatively within the Born approximation, valid for the metallic regime. We consider an eight-band Kohn-Luttinger model (six valence bands plus two conduction bands) as well as a ten-band model with additional dispersionless bands simulating phenomenologically the upper-mid-gap states induced by antisite and interstitial impurities. These models qualitatively account for optical-absorption experiments and predict new features in the mid-infrared Kerr angle and magnetic-circular-dichroism properties as a function of Mn concentration and free carrier density.