EFFECTS OF ELECTRON CORRELATIONS ON AUGER-ELECTRON AND APPEARANCE-POTENTIAL SPECTRA OF SOLID-SURFACES

Abstract

In the past the Cini-Sawatzky model and its generalizations to arbitrary band-filling and orbital degeneracy have been employed extensively in the discussion of electron-correlation effects in CVV Auger-electron (AE) and appearance-potential (AP) spectra of solid surfaces. In all these attempts, however, the strong inherent perturbation of the valence-band system due to the core-hole potential has been neglected up to now. We present results of a new theoretical approach for arbitrary band-filling, which for the first time accounts for the on-site Coulomb interaction among the valence-band electrons U and for the Coulomb interaction between valence-band and core electrons U(c) as well. The AE- and AP-intensities are given by a three-particle Green function, which is calculated using a diagrammatic vertex-correction method. The spectra show a strong dependence on the valence-band-core interaction U(c) and exhibit several satellite features in the strong-correlation case. They indicate the importance of an accurate description of the effects of the core-hole potential for AE- and AP-spectra of solids.