6533b871fe1ef96bd12d18ad

RESEARCH PRODUCT

X-ray absorption near edge spectroscopy at the Mn K-edge in highly homogeneous GaMnN diluted magnetic semiconductors

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We have studied by X-ray absorption spectroscopy the local environment of Mn in highly homogeneous Ga 1-x Mn x N (0.06 <x<0.14) thin epilayers grown by molecular beam epitaxy on [0001] SiC substrates. The measurements were performed in fluorescence mode around the Ga and Mn K-edges. In this report, we focus our attention to the X-ray absorption near edge spectroscopy (XANES) results. The comparison of the XANES spectra corresponding to the Ga and Mn edges indicates that Mn is substitutional to Ga in all samples studied. The XANES spectra measured at the Mn absorption edge shows in the near-edge region a double peak and a shoulder below the absorption edge and the main absorption peak after the edge, separated around 15 eV above the pre-edge structure. We have compared the position of the edge with that of MnO (Mn 2+ ) and Mn 2 O 3 (Mn 3+ ). All samples studied present the same Mn oxidation state, 2 + . In order to interprete the near-edge structure, we have performed ab initio calculations with a 2 x 2 x 1 supercell (∼6% Mn) using the full potential linear augmented plane wave method as implemented in the Wien2k code. The calculations show the appearance of Mn anti-bonding t 2g bands, which are responsible for the pre-edge absorption. The shoulder and main absorption peaks are due to transitions from the valence band Is-states of Mn to the p-contributions of the conduction bands.