Interconfigurational excitation energy

The pressiue dependence of the electrical resistivity of YbCuAl was investigated (Alami-Yadri et al. 1998, 1999a,b) up to 8 GPa. The resistivity at 300 K decreases with increasing pressure. At 8 GPa a dependence occurs at low temperature (Fermi-liquid behavior), and the Kondo temperature decreases with increasing pressure. The experimental setup for these measurements was presented by Jaccard et al. (1998). Furthermore, point-contact spectroscopy was used to measure the interconfigurational excitation energies and conduction-electron lifetime width of valence-fluctuating YbCuAl (Bussian et al. 1982). 

Fig. 1. Schematic energy level diagram of the in-terconfigurational fluctuation (ICF) model describing valence fluctuations between two 4f configurations (4r, 4r ), characterized by their /multiplet level structure. The basic parameters of the ICF model and denote the interconfigurational excitation energy and interconfigurational mixing width, respectively.

Fig. 8. Temperature dependence of (a) the interconfigurational excitation energy ( ,) and (b) the upper limit of the fluctuation temperature T, of EuPd Sij as directly revealed in the Raman spectra of fig. 5.

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