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  Wolska, A. ; Lawniczak-Jablonska, K. ; Sadowski, J. ; Holub-Krappe, E. ; Persson, A. ; Arvanitis, D.: Towards MnAs nano-clusters in (GaMnAs): L-edge XANES upon post growth annealing. In: Johansson, U. [u.a.] [Eds.] : MAX-Lab Activity Report 2007Lund, 2008, p. 400-401

Abstract:
Ga1-xMnxAs is commonly considered as a promising material for mi- croelectronic applications utilizing the electron spin. One of the ways that allow increasing the Curie temperature above room temperature is to pro- duce second phase inclusions. In this paper Ga1-xMnxAs samples containing precipitations of ferromagnetic MnAs are under consideration. We focus on the atomic and electronic structure of the Mn atoms relating to the clus- ter formation. The changes in the electronic structure of the Mn, Ga and As atoms in the (Ga,Mn)As layers after high temperature annealing were determined by X-ray absorption near edge spectroscopy. The experimental spectra were compared with the predictions of ab initio full multiple scat- tering theory using the FEFF 8.4 code. The nominal concentration of the Mn atoms in the investigated samples was 6% and 8%. We do not observe changes in the electronic structure of Ga and As introduced by the presence of Mn atoms. We find, in contrast, considerable changes in the electronic structure around the Mn atoms. Moreover, for the first time it was possible to indicate preferred interstitial positions of Mn atoms.