Exchange interaction for Mn acceptor in GaAs: revealing its strong deformation dependence

TL;DR

This study calculates the exchange interaction between Mn ions and holes in GaAs, revealing a significant dependence on lattice deformation that explains experimental magnetic susceptibility variations at high temperatures.

Contribution

It provides a detailed microscopic calculation of the exchange interaction's deformation dependence, linking it to experimental observations and high-temperature magnetic behavior.

Findings

Exchange interaction varies significantly with lattice strain.

Deformation dependence explains high-temperature magnetic susceptibility discrepancies.

Strain effects can alter exchange coupling by over 50%."

Abstract

In this paper we calculate exchange interaction constant between manganese ion inner electronic $d$-shell and GaAs valence band bounded hole using their microscopic multiparticle wave functions. We reveal its parametric dependence on crystal lattice deformations and find out that it could be about and even more than dozens percent when the strain tensor reaches values of $10^{-3} \div 10^{-2}$. This fact is in accordance with the previous hypothesis of deformation dependence of Mn acceptors in GaAs fine energy structure obtained from Raman spectroscopy, and we show that this dependence has the same magnitude. Also, we resolve here the problem of a substantial high temperature mismatch between well-developed theory and experimental data for the static magnetic susceptibility of Mn ions in GaAs. We show by numerical estimates and calculations that quite a strong parametric dependence of the exchange coupling value on GaAs lattice expansion determines the high temperature (above $50~$K) magnetic susceptibility reduction as well.