Theory Meets Experiment in Low-Dimensional Structures with Correlated Electrons
Prague, Czech Republic, July 1 – 4, 2019
The theory of continuum charge excitations in high-valence transition-metal oxides revealed by resonant inelastic x-ray scattering
We present a computational study of L-edge resonant inelastic x-ray scattering (RIXS) in 3d high-valence transition-metal (TM) oxides: RNiO3 (R: rare-earth element); LaCuO3 and NaCuO2 . We employ a theoretical approach based on local density approximation (LDA) and dynamical mean-field theory (DMFT), where the Anderson impurity model with DMFT hybridization function is extended to include TM 2p core orbitals. The heart of the present approach is the configuration-interaction-based exact-diagonalization impurity solver that allows to include the low-energy electron-hole pairs accurately, necessary to describe RIXS in the high-valence materials with negative charge-transfer energy. The LDA+DMFT approach enables to describe both bound and unbound electron-hole pair excitations in the RIXS spectra. In this talk, we discuss the behavior of the fluorescence-like (FL) feature and how it is connected to the low-energy valence states and crystal structure. Special attention will be paid to the selection rules for the visibility of the FL RIXS feature, that reflect the lattice geometry around the x-ray excited TM site. Our results reproduce the recent experimental data for RNiO3 .
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