Effects of Ce Doping on Electronic Structures of Ln2-xCexCuO4 (Ln=Nd, Sm, Eu, Gd) Studied by Core-Level Photoemission Spectroscopy

Abstract
We have investigated the changes in the electronic structures of Ln2-x Ce x CuO4 (Ln=Nd, Sm, Eu and Gd) upon Ce doping using core-level X-ray photoemission spectroscopy. For Ln2-x Ce x CuO4, the O 1s spectra exhibit a single-peaked structure. The energy positions of the O 1s lines are shifted toward the high binding energy side with increasing Ce concentration. For the Cu 2p spectra, the intensity ratio of the satellite to the main peaks decreases with increasing Ce concentration. This decrease can be explained by the presence of Cu1+ under Ce doping.