X-ray photoemission spectrum, electronic structure, and magnetism of UCuxSb2

The room temperature valence and core-level X-ray photoemission spectra of an UCu0.83Sb2 single crystal were measured using the Al K alpha source. The related theoretical valence spectra were determined from densities of states for UCuxSb2 systems obtained from our band structure calculations using the FLAPW method in the LDA + U approximation, as implemented in the Wien2k code, and the supercell approach to simulate a deficit of the Cu atoms. The calculated spectrum of the Cu-deficit UCu0.75Sb2 is in good accord with the experimental one, revealing a complete localization of the Cu 3d electrons and a dual (both localized and itinerant) behavior as well as unusual spin-up polarization of the U 5f states near the Fermi level. Our calculated total magnetic moments on the uranium atom are in reasonable agreement with the experimental value of magnetization. Some localization and valence-mixing of the 5f-electrons are reflected by the triple-satellite (sats. 1-eV, 3-eV and 7-eV) structure, visible in the spectrum of the U 4f core-lines. Also the calculated Fermi surface of the stoichiometric system is complex, containing five spin-polarized sheets of different dimensionality with some nesting features. (C) 2015 Elsevier B.V. All rights reserved.