Electronic structure and the S K absorption spectra of chromium-containing chalcogenide spinels Cd1−x CuxCr2S4

Abstract

The electronic structure and x-ray absorption spectra of sulfur in normal ferromagnetic spinels of the general formula Cd1−xCuxCr2S4 (x=0.05, 0.1, 0.15, 0.2) are calculated using the FEFF8 program. In these calculations, the self-consistent crystal potential is simulated in terms of the partially nonlocal model of exchange-correlation potential. The model is based on the Dirac-Fock approximation for core electrons and the Hedin-Lundquist approximation for valence electrons. The S K absorption edges are calculated in the approximation of full multiple scattering by a 27-atom cluster. In addition, one-, two-, and three-scattering paths within a 981-atom clusters are taken into account. The calculation demonstrates that the introduction of even insignificant amounts of copper atoms into a CdCr2S4 cluster leads to a shift in the main features of the S K adsorption edges toward the high-energy range. This can be associated with variations in the nearest environment of the absorbing atom and active participation of copper ions in the chemical bonding of chalcogenide spinels.