Charge and Spin Excitation Spectra in the Degenerate Anderson Model

Abstract

The charge and spin excitation spectra in the degenerate Anderson model are calculated by means of the exact solution. We investigate a crossover behavior in the excitation spectra. When the f -level position shifts from the valence fluctuation regime to the Kondo regime, the broad asymmetric peak structure in the charge excitation spectrum changes into the universal one around the bare f -level position. In the case of the spin excitation, the spectrum gets narrower and forms the sharp Kondo resonance with the hump structure arising from the orbital degeneracy. The crystal-field effects on the spin excitation spectra are also investigated in the Kondo limit. As the crystal-field splitting is increased, the Kondo resonance gets narrower and the hump structure disappears.