Electronic Structure of Electron-Doped Superconductor Nd2-xCexCuO4 from the Analysis of Cu 2p-XPS

The role of the Cu As conduction band in the Cu 2p-XPS (X-ray photoemission spectrum) of Nd2_xCexCuO4 is investigated on the basis of both a simple CuO4 cluster model and the impurity Anderson model. The impurity Anderson model consists of the impurity Cu 3d shell and the valence and conduction bands which are obtained from the O 2p and Cu As bands by the tight-binding approximation. From the carrier concentration dependence of the Cu 2p-XPS, the electron doping mechanism is discussed. If the Cu 4s level is lower in energy than that estimated from the energy band calculation by a few eV, the doped electrons are shown to occupy the Cu As band in the low-doping regime.