Local approach to electronic excitations in MnO, FeO, CoO, and NiO.

Abstract

The excitation spectra of the antiferromagnetic transition-metal oxides MnO, FeO, CoO, and NiO are studied by developing a local three-body scattering theory within a multiorbital tight-binding model. The self-energy corrections to the Hartree-Fock solutions are carried out by taking account of local three-body correlations. Thereby the multiplet structures of three-particle states are fully taken into account. It is shown that the self-energy correction improves drastically the excitation spectra for FeO, CoO, and NiO, leading to the correct value of the band gap and the satellite structure, in agreement with photoemission experiments. Quasiparticle dispersions are obtained in good agreement with the angle-resolved photoemission data of CoO and NiO. The self-energy correction for MnO is found to be quite small. \textcopyright{} 1996 The American Physical Society.