Epitaxial thin films of LaNiO 3−x were deposited by using a reactive d.c. magnetron sputtering technique. High-energy X-ray photoelectron spectroscopy was used to analyze the composition and valence states of La and Ni in the films after long time aging in atmosphere. The obtained results show the existence lanthanum and nickel in oxide and hydroxide chemical states. The oxygen exists in four chemical states: lattice oxides, hydroxyl groups and in adsorbed water. Comparison of the spectra recorded at normal emission and grazing emission angle revealed that the hydroxyl group's concentration is mostly present at the surface of the film.

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We present the experimental and theoretical study of correlation effects in epitaxial SrRuO 3 thin films. Experimentally, we have performed resonant ultraviolet photoemission spectroscopy (UPS) and angle-resolved hard x-ray photoemission spectroscopy (HAXPES) measurements. For resonant UPS, the two methods, Fanoprofile fitting of constant initial state spectra and the energy distribution curves equidistant difference spectra, were used to extract Ru 4d partial spectral weight (PSW) in the valence band. We find Ru 4d PSW possessing a clearly pronounced coherent peak at the Fermi level together with angle-resolved HAXPES spectra demonstrating no difference in surface and bulk electronic structure. From comparison of experimental data with theoretical calculations done at density functional theory level, we conclude that SrRuO 3 is a weakly correlated material and electronic structure of it can be consistently described employing first-principles approaches.

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We present the experimental and theoretical study of x-ray photoelectron spectroscopy spectrum of LaNiO 3−x thin films deposited onto a ͑100͒-plane oriented NdGaO 3 substrate by applying a reactive dc magnetron sputtering technique. The crystal calculations carried out within pure density functional theory ͑DFT͒ approximation properly reproduce the delocalized valence band showing the suitability of homogeneous electron gas model, whereas hybrid DFT/Hartree-Fock ͑HF͒ calculations work out in the core region indicating the localized nature of core electrons. The significance of spin-orbit coupling to the electronic structure of LaNiO 3 is revealed by relativistic molecular HF study allowing to theoretically identify the doublet splitting of La 5p. Electron-density difference map indicates a different nature of La-O and Ni-O chemical bonds in LaNiO 3 while the Mulliken population analysis adds information about the charge distributions and overlap populations between separate atoms.

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Thin LaNiO 3−δ films with pseudocubic (100) preferred orientation were prepared by reactive DC magnetron sputtering and in situ annealed in O2 and vacuum. X-ray photoelectron spectroscopy (XPS) was used to determine the variation in composition of the films under high temperature annealing. The experimental O 1s and La 3d -Ni 2p 3/2 spectra of LaNiO 3−δ films was analysed in terms of O 2− , O − /(OH) − , and weakly adsorbed oxygen species. It was shown that the change in the type of conductivity from metallic to semiconducting one is accompanied by a marked increase in the intensity of the lateral (∼531 eV) peak of oxygen. The quantitative analyses of La 3d -Ni 2p 3/2 spectra show that the Ni/La concentration ratio significantly decreases after heating above the dehydration temperature. These variations in conductivity and surface composition were attributed to the loss of lattice oxygen with subsequent adsorption of O − and (OH) − anions and weakly adsorbed oxygen species from ambient air.