Thermopower in Ce Kondo Systems

The giant thermopower in metals with Ce³⁺ impurities is theoretically studied. The relaxation time of a conduction electron is calculated as a function of energy in the selfconsistent ladder approximation by applying Abrikosov's pseudofermion technique to the Coqblin-Schrieffer exchange model with crystal field. The thermopower as well as the electrical resistivity exhibit universal behaviors if the crystal field is neglected. The crystal field induces the characteristic features and the anisotropy in the thermopower versus temperature curve. However, the sign of the thermopower is always positive in Ce system in contrast with Yb systems.