Electronic structure of Nd2CuO4−yFy and Nd2−xCexCuO4−δ studied by photoemission spectroscopy

Abstract Resonant photoemission spectroscopy was used to identify the various features in the valence band spectra of these n-type superconducting materials. On doping no significant changes in the occupied density of states are observed, except the narrow F 2p-peak in the F-doepd system. Core-level spectroscopy revealed, that CE is tetravalent in these compounds, and that the trivalence of Nd is not affected by the presence of F. In both cases a significant, doping-dependent admixture of Cu 3+ to the Cu 3d 9 -states is observed.