Electronic excitations of magnetic impurity state in diluted magnetic semiconductor (Ga,Mn)As

TL;DR

This study investigates the electronic excitations of Mn impurities in (Ga,Mn)As using RIXS, revealing that Mn exists mainly in a $d^4$ configuration with broad excitations due to rapid decay into electron-hole pairs.

Contribution

The paper provides a detailed analysis of Mn electronic states in (Ga,Mn)As using RIXS and configuration-interaction models, highlighting charge transfer effects and excitation broadening.

Findings

Mn in (Ga,Mn)As is mainly in a $d^4$ state.

Broad $d$-$d$ excitations are observed due to finite lifetime effects.

Charge transfer states dominate the RIXS spectra.

Abstract

The electronic structure of doped Mn in (Ga,Mn)As is studied by resonant inelastic X-ray scattering (RIXS). From configuration-interaction cluster-model calculations, the line shapes of the Mn $L_3$ RIXS spectra can be explained by $d$-$d$ excitations from the Mn$^{3+}$ ground state, dominated by charge-transferred states, rather than a Mn$^{2+}$ ground state. Unlike archetypical $d$-$d$ excitation, the peak widths are broader than the experimental energy resolution. We attribute the broadening to a finite lifetime of the $d$-$d$ excitations, which decay rapidly to electron-hole pairs in the host valence and conduction bands through hybridization of the Mn $3d$ orbital with the ligand band.