Theoretical study of resonant inelastic X-ray scattering spectrum in nickelates

We examine theoretically the Resonant Inelastic X-ray Scattering (RIXS) spectra on nickelates by using numerically exact diagonalization techniques on the two-band Hubbard model. Other spectra such as the dynamical charge correlation function are examined to discuss what excitations appear in the RIXS. We demonstrate that the spectra which appear upon doping in the dynamical charge correlation function and the RIXS are originated from only high spin states, in contrast to the optical conductivity where the spectrum comes from both high and low spin states.