Doping and Momentum Dependence of Charge Dynamics in Nd2−xCexCuO4 (x = 0, 0.075, and 0.15) Studied by Resonant Inelastic X-ray Scattering

Abstract

We report a resonant x‐ray scattering (RIXS) study at Cu K‐edge in the n‐type cuprate superconductor Nd2−xCexCuO4 from the half‐filled Mott insulator to the Tc = 25 K superconductor. The Mott gap is clearly seen in the spectra of x = 0, while both interband excitation across the Mott gap and intraband excitation in the upper Hubbard band are observed at electron‐doped x = 0.075 and 0.15. The momentum dependence of x = 0.075 is presented and the dispersion relation of x = 0.075 is qualitatively similar to that of x = 0.15. We find in the doping dependence that the intraband excitation at low energy increase in intensity with carrier concentration (x).