Electron-hole contribution to the apparent s-d exchange interaction in III-V diluted magnetic semiconductors

TL;DR

This paper explains the unusual sign and size of the apparent s-d exchange interaction in III-V Mn-based diluted magnetic semiconductors by considering electron-hole interactions, revealing they dominate over direct electron-Mn spin coupling.

Contribution

It introduces a theoretical model showing that electron-hole interactions significantly influence the apparent s-d exchange in these materials, challenging previous assumptions.

Findings

Electron-hole interactions explain the sign and magnitude of the apparent s-d exchange.

Coulomb potentials at Mn acceptors reduce the exchange in n-type materials.

The dominant role of electron-hole interactions over direct electron-Mn coupling is demonstrated.

Abstract

Spin splitting of photoelectrons in p-type and electrons in n-type III-V Mn-based diluted magnetic semiconductors is studied theoretically. It is demonstrated that the unusual sign and magnitude of the apparent s-d exchange integral reported for GaAs:Mn arises from exchange interactions between electrons and holes bound to Mn acceptors. This interaction dominates over the coupling between electrons and Mn spins, so far regarded as the main source of spin-dependent phenomena. A reduced magnitude of the apparent s-d exchange integral found in n-type materials is explained by the presence of repulsive Coulomb potentials at ionized Mn acceptors and a bottleneck effect.