Analysis of surface-bulk screening competition in the electron-doped Nd2-xCexCuO4 cuprate using x-ray photoemission spectroscopy

We report core level and valence band photoemission results obtained for Nd2-xCexCuO4 (x = 0.15) single crystals and films by using both soft and hard x rays, hence, with tunable depth sensitivity. When using hard x rays only, we observe distinct and energy separated structures in the main 2p(5)3d(9)L peak of Cu 2p(3/2) and 2p(1/2) core levels, including the well screened features located at the high kinetic energy side, which were recently reported by Taguchi et al. [Phys. Rev. Lett. 95, 177002 (2005)]. By varying the photoelectron takeoff angle, we analyze the difference in the screening properties between surface and bulk, and we demonstrate the depth dependence of the electronic properties by following the evolution of the bulk-related peak. The possible influence of the surface conditions on the Cu 2p spectral features is also discussed.