| Cu K-edge Resonant inelastic x-ray scattering (RIXS) in two-dimensional insulating cuprates reveals characteristic momentum dependence of a charge-transfer process from the occupied Zhang-Rice singlet band to the unoccupied upper Hubbard band, i.e., Mott-gap excitation. Using the numerically exact diagonalization technique for finite-size Hubbard cluster, we have proposed that the Mott-gap excitations are seen in the Cu K-edge RIXS even for doped cuprates but with different doping dependence between hole- and electron-doping. Recently we examined theoretically the Cu K-edge RIXS on electron-doped Nd2-x Cex CuO4 and compared with the experimental data obtained in SPring-8. The low-energy spectrum is assigned as the intra-band excitation and is qualitatively similar to the dynamical charge correlation function. These results indicate that the RIXS is a powerful technique to investigate the charge dynamics in the strongly correlated electron systems. |
|