Response properties of III-V dilute magnetic semiconductors: interplay of disorder, dynamical electron-electron interactions and band-structure effects

TL;DR

This paper develops a comprehensive theory for the electronic response in III-V dilute magnetic semiconductors like GaMnAs, incorporating disorder, electron-electron interactions, and band structure effects to explain optical properties.

Contribution

It combines a detailed valence band model with first-principles disorder calculations and a dynamic electron-electron interaction approach, providing new insights into carrier relaxation and optical conductivity.

Findings

Collective excitations increase carrier relaxation rates.

Relaxation rate changes have minor impact on infrared optical conductivity.

Theoretical results agree with experimental measurements.

Abstract

A theory of the electronic response in spin and charge disordered media is developed with the particular aim to describe III-V dilute magnetic semiconductors like GaMnAs. The theory combines a detailed k.p description of the valence band, in which the itinerant carriers are assumed to reside, with first-principles calculations of disorder contributions using an equation-of-motion approach for the current response function. A fully dynamic treatment of electron-electron interaction is achieved by means of time-dependent density functional theory. It is found that collective excitations within the valence band significantly increase the carrier relaxation rate by providing effective channels for momentum relaxation. This modification of the relaxation rate, however, only has a minor impact on the infrared optical conductivity in GaMnAs, which is mostly determined by the details of the valence band structure and found to be in agreement with experiment.