Resonant photoemission of LaNiO3-δthin films

Thin LaNiO 3-δ films with pseudocubic (100) preferred orientation were prepared by reactive DC magnetron sputtering and annealed at ultra high vacuum above dehydration temperature.The resonant photoemission spectroscopy was used to study the surface composition and electronic structure under La 4d→4f and Ni 3p→3d photoexcitation.The resonance features observed in core level and valence band spectra under La 4d→4f transition were explained in terms of autoionization process and lanthanum-oxygen valence band states' hybridization.No resonant features were observed in the valence band spectra under Ni 3p→3d excitation indicating that nickel species are not present at the LaNiO 3-δ film surface after heat treatment.