Condensed-Matter Physics & Materials Science Seminar

I will present our work on the theoretical investigation of the electronic structure, magnetic interactions and resonant inelastic X-ray scattering (RIXS) in 3d or 4d-5d transition metal (TM) compounds by using wave-function-based many-body quantum chemistry (QC) methods. My presentation contains two parts. In the first part, I will discuss the magnetic properties of 4d and 5d TM ions with a formally degenerate t12g electron configuration in the double-perovskite (DP) materials Ba2YMoO6, Ba2LiOsO6 and Ba2NaOsO6. Our analysis indicates that the sizable magnetic moments and g-factors found experimentally are due to both strong TM d – ligand p hybridization and dynamic Jahn-Teller effects. Our results also point out that cation charge imbalance in the DP structure allows a fine tuning of the gap between the t2g and eg levels. In another example of t12g electron configuration, spin-Peierls (SP) TiPO4 compound, we assign excitation peaks of experimental RIXS spectra and find that the d1 ground state is composed of an admixture of dz2 and dxz orbital character. In the second part, I will discuss a computational scheme for computing intensities as measured in X-ray absorption and RIXS experiments. We take into account the readjustment of the charge distribution in the 'vicinity' of an excited electron for the modeling of RIXS. The computed L3-edge RIXS spectra for Cu2+ 3d9 ions in KCuF3 and for Ni2+ 3d8 ions in La2NiO4 reproduce trends found experimentally for the incoming-photon incident-angle and polarization dependence.