I. Di Marco, P. Thunström, M. I. Katsnelson, J. Sadowski, K. Karlsson, S. Lebègue, J. Kanski, O. Eriksson
We report an experimental and theoretical study of the valence electron spectrum of the dilute magnetic semiconductor (DMS) material, Mn doped GaAs. The experimental data are obtained through the differences between off- and on-resonance photoemission data for several concentrations of Mn atoms. The theoretical electronic structure is calculated by means of a combination of density-functional theory in the local density approximation and dynamical mean-field theory (LDA+DMFT), using exact diagonalisation as an impurity solver. Theory is found to accurately reproduce measured data, and illustrates the importance of correlation effects in Mn doped GaAs, and that quite likely correlations effects are significant in DMS materials in general. In addition, our results demonstrate the presence of Mn states at the top of the valence band, and we argue that the double-exchange interaction is a significant driving mechanism for the ferromagnetic order in this material.
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http://arxiv.org/abs/1207.2887
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