High-Energy Spectroscopy in Oxide Superconductors

We consistently analyze the Cu 2p-XPS, L₃-XAS, 3d-XPS and resonant XPS in high-T_c superconducting materials, such as (La_1-xSr_x)₂CuO₄ and YBa₂Cu₃O_7-τ on the basis of the impurity Anderson model. We introduce five valence bands into the model to take account of the anisotropic nature of the Cu 3d orbitals and the different 2p energy levels for nonequi valent O sites. The key parameter values which characterize these Cu 3d and O 2p states are estimated from the analysis, and their trends are discussed. We study the effect of hole doping on the 2p-XPS and L₃-XAS, especially on the polarization dependence of Z,₃-XAS. For reference, we also analyze the spectra of CuO.