The influence of electrostatic potentials on the apparent s-d exchange energy in III-V diluted magnetic semiconductors

TL;DR

This paper extends the muffin-tin model to include electrostatic potentials in III-V diluted magnetic semiconductors, explaining the reduced apparent s-d exchange energy and its dependence on Mn concentration.

Contribution

The study introduces an extended model accounting for electrostatic effects, providing insights into the behavior of electron spin splitting in Mn-doped III-V semiconductors.

Findings

Electrostatic potentials reduce the apparent s-d exchange coupling.

The reduction effect increases as Mn concentration decreases.

The model explains recent experimental observations of spin splitting.

Abstract

The muffin-tin model of an effective-mass electron interacting with magnetic ions in semiconductors is extended to incorporate electrostatic potentials that are present in the case of Mn-based III-V compounds (${Ga}_{1-x} {Mn}_x {N}$, ${Ga}_{1-x} {Mn}_x {As}$). Since the conduction band electron is repelled from negatively charged magnetic ions and attracted by compensating donors, the \emph{apparent} value of the s-d exchange coupling $N_0 \alpha$ is reduced. It is shown that the magnitude of this effect increases when x diminishes. Our model may explain an unusual behavior of electron spin splitting observed recently in those two materials in the Mn concentration range x <= 0.2%.