Charge-transfer effect in hard x-ray 1s and 2p photoemission spectra: LDA+DMFT and cluster-model analysis

Abstract

We study 1s and 2p hard x-ray photoemission spectra (XPS) in a series of late transition metal oxides: Fe2O3 (3d5), FeTiO3 (3d6), CoO (3d7), and NiO (3d8). The experimental spectra are analyzed with two theoretical approaches: MO6 cluster model and local density approximation (LDA) + dynamical mean-field theory (DMFT). Owing to the absence of the core-valence multiplets and spin-orbit coupling, 1s XPS is found to be a sensitive probe of chemical bonding and nonlocal charge-transfer screening, providing complementary information to 2p XPS. The 1s XPS spectra are used to assess the accuracy of the ab initio LDA+DMFT approach, developed recently to study the material-specific charge-transfer effects in core-level XPS.