Ferromagnetism in Ga1-xMnxP: evidence for inter-Mn exchange mediated by localized holes within a detached impurity band

TL;DR

This study shows that ferromagnetism in Ga1-xMnxP is mediated by localized holes within a Mn impurity band, with evidence from optical and magnetic measurements indicating a distinct impurity band not merged with the valence band.

Contribution

It provides direct evidence that ferromagnetism in Ga1-xMnxP is mediated by holes in a Mn-derived impurity band, distinct from the valence band, and characterizes the magnetic and transport properties.

Findings

Presence of a Mn impurity band separate from the valence band for x<0.06

Carrier-mediated ferromagnetism confirmed by anomalous Hall effect

Electrical transport dominated by impurity band excitation above TC

Abstract

We demonstrate that in ferromagnetic Ga1-xMnxP exchange is mediated by holes localized in a Mn-derived band. For x<0.06, infrared absorption and photoconductivity spectra indicate the presence of a Mn impurity band which is not merged with the valence band. At temperatures above TC (<65 K) electrical transport is dominated by excitation across this energy gap while nearest neighbor hopping dominates below TC. Magnetization measurements reveal a moment of 3.5 Bohr magnetons per substitutional Mn, while the large anomalous Hall signal unambiguously demonstrates that the ferromagnetism is carrier-mediated.