Effects ofd−fcorrelation on the mixed-valent properties of Ce systems

In a recent paper it was suggested that the double-peak $4f$ photoemission spectra of Ce and ${\mathrm{Ce}}_{0.9}$ ${\mathrm{Th}}_{0.1}$ indicate strong $d-f$ correlation. This paper discusses the effects of this correlation on the mixed-valent properties of Ce systems. In the impurity-lattice approximation, which is valid at high temperatures, the $f$-electron spectrum has the well-known x-ray-edge singularity at the Fermi level. The inclusion of $d-f$ hybridization adds fine structures to the spectrum near the Fermi level. Furthermore, the singularity can account for the Kondo-type resistivity and specific-heat anomalies without the need to invoke spin-flip scattering.