High-Energy Spectroscopy in Oxide Superconductors

Abstract

We consistently analyze the Cu 2 p -XPS, L 3 -XAS, 3 d -XPS and resonant XPS in high- T c superconducting materials, such as (La 1- x Sr x ) 2 CuO 4 and YBa 2 Cu 3 O 7-δ , 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 3 d orbitals and the different 2 p energy levels for nonequivalent O sites. The key parameter values which characterize these Cu 3 d and O 2 p states are estimated from the analysis, and their trends are discussed. We study the effect of hole doping on the 2 p -XPS and L 3 -XAS, especially on the polarization dependence of L 3 -XAS. For reference, we also analyze the spectra of CuO.