Multiband tight-binding model of local magnetism in GaMnAs

TL;DR

This paper models local magnetism in GaMnAs using a multiband tight-binding approach, revealing how Mn impurities influence the local density of states and magnetic interactions, which can be experimentally probed via scanning tunneling spectroscopy.

Contribution

It introduces a detailed multiband tight-binding model for GaMnAs that captures the effects of Mn impurities on local electronic and magnetic properties.

Findings

Local spin-polarized resonances enhance LDOS near band edges.

Hybridization of Mn acceptor states depends on impurity separation.

Scanning tunneling spectroscopy can measure Mn-Mn interactions.

Abstract

We present the spin and orbitally resolved local density of states (LDOS) for a single Mn impurity and for two nearby Mn impurities in GaAs. The GaAs host is described by a sp^3 tight-binding Hamiltonian, and the Mn impurity is described by a local p-d hybridization and on-site potential. Local spin-polarized resonances within the valence bands significantly enhance the LDOS near the band edge. For two nearby parallel Mn moments the acceptor states hybridize and split in energy. Thus scanning tunneling spectroscopy can directly measure the Mn-Mn interaction as a function of distance.