Characterization of Fe 3d states in CuFeS2 by resonant X-ray emission spectroscopy

Resonant X-ray emission spectroscopy (RXES) experiments were carried out in a single crystal of chalcopyrite CuFeS2, an anti ferromagnetic semiconductor with a golden lustre, to unravel the overlapping d-d and charge-transfer transitions extending well above the absorption edge, which cannot be observed by conventional optical absorption experiments. The observed RXES spectra have been analyzed by means of cluster-model calculation with configuration interaction, which leads to the conclusion that CuFeS2 is a Haldane-Anderson insulator with a negative value of charge transfer energy, Delta = -3 eV. (c) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim