XANES studies of Mn K and L-3,L-2 edges in the (Ga,Mn) As layers modified by high temperature annealing

In English Ga1-xMnx As is commonly considered as a promising material for microelectronic applications utilizing the electron spin. One of the ways that allow increasing the Curie temperature above room temperature is to produce second phase inclusions. In this paper Gal-,Mn.As samples containing precipitations of ferromagnetic MnAs are under consideration. We focus on the atomic and electronic structure around the Mn atoms relating to the cluster 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 scattering 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 Ca and As introduced by the presence of the 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 the preferred interstitial positions of the Mn atoms.