Theory of resonant x-ray emission spectra in compounds with localized f electrons

Abstract

I discuss a theoretical description of the resonant x-ray emission spectroscopy (RXES) that is based on the Anderson impurity model. The parameters entering the model are determined from material-specific LDA+DMFT calculations. The theory is applicable across the whole f series, not only in the limits of nearly empty (La, Ce) or nearly full (Yb) valence f shell. Its performance is illustrated on the pressure-enhanced intermediate valency of elemental praseodymium. The obtained results are compared to the usual interpretation of RXES, which assumes that the spectrum is a superposition of several signals, each corresponding to one configuration of the 4f shell. The present theory simplifies to such superposition only if nearly all effects of hybridization of the 4f shell with the surrounding states are neglected. Although the assumption of negligible hybridization sounds reasonable for lanthanides, the explicit calculations show that it substantially distorts the analysis of the RXES data.

LDA+DMFTapproach to resonant inelastic x-ray scattering in correlated materials

“…In this paper, we calculate L-edge RIXS spectra for a series of TM oxides using an ab initio approach based on local density approximation (LDA) + dynamical meanfield theory (DMFT) [20][21][22]. This approach [23,24] is a generalization of the cluster model. It allows to include the continuum of unbound electron-hole pairs as * A.H and M.W contributed equally to this work well as the CT excitations in a material-specific manner, while retaining the single-impurity description.…”

Charge-transfer effect in hard x-ray1sand2pphotoemission spectra:LDA+DMFTand cluster-model analysis

“…[31] in a similar direction. The unified impurity-model description of core-level spectra in a wide range of correlated materials [32] and in various excitation processes/edges [30,33] provided by the LDA+DMFT approach is posted to experimental tests.…”

Core-Level X-Ray Spectroscopy of Infinite-Layer Nickelate: LDA+DMFT Study

“…In this paper, we use the local-density approximation (LDA) + dynamical mean-field theory (DMFT) [24][25][26] to calculate XPS, XAS and RIXS spectra [16,[27][28][29][30] of undoped infinite-layer nickelates. By comparison with the available experimental data we identify the most appropriate the CT energy and use it for classification within the Zaanen-Sawatzky-Allen scheme [10].…”