Hole Transport in Impurity Band and Valence Bands Studied in Moderately Doped GaAs:Mn Single Crystals

TL;DR

This study investigates the temperature-dependent electrical transport in GaMnAs single crystals with low Mn doping, revealing that the metal-insulator transition occurs within the impurity band separate from the valence band.

Contribution

It provides experimental evidence that the metal-insulator transition in GaAs:Mn occurs within the impurity band, challenging previous assumptions about the valence band involvement.

Findings

Impurity band transport shows metallic behavior at ~0.3 at.% Mn.

Metal-insulator transition occurs within the impurity band, not the valence band.

High temperature solubility limit of Mn in GaAs discussed.

Abstract

We report on simple experiment on temperature-dependent Hall effect measurements in GaMnAs single crystalline samples with Mn composition estimated at 0.05-0.3 at.% which is slightly below the onset of ferromagnetism. Impurity band transport is visible for Mn compositions of ~0.3 at.% as a clear metallic behaviour. The results show interesting situation that the Metal-Insulator transition in GaAs:Mn occurs within the impurity band which is separated from the valence bands for Mn concentrations studied here. We also discuss on the equilibrium high temperature solubility limit of Mn in GaAs, unknown precisely in the literature.