The possibility of exciton formation is studied in a model which allows for hybridization between a conduction band and a 4f level and which takes into account the scattering of electrons in a band of higher energy on the 4f ion. There is no direct coupling between this latter band and the conduction band. For weak scattering and in the Hartree-Fock approximation an isolated level built up from the 4f and the higher-band states appears. For sufficiently strong scattering this level broadens due to the coupling to the conduction band and becomes partially occupied. The theoretical arguments are supported by numerical calculations.
ASJC Scopus subject areas
- Condensed Matter Physics