Antiferromagnetism and Superconductivity in a Heavy Fermion System.

Specific heat, zero field and high field resistivity, and magnetic susceptibility measurements on the heavy fermion system CePb(,3) have been carried out and show that CePb(,3) has a giant electronic coefficient of specific heat, has a very low Kondo temperature, is magnetically ordered at 1.1 K, undergoes a superconducting transition as it is cooled even lower, and is driven into a superconducting state under high magnetic fields. Upon dilution of the Ce by La, a scaling behavior in the (rho), C and (chi) data was observed and it was found that heavy fermion behavior exists not only in the concentrated system but also in the diluted system. Upon substitution of Sn for Pb, a dramatic change in behavior from (nearly) trivalent (CePb(,3)) to mixed valent (CeSn(,3)) was observed. All the measurements were found to be in good agreement with the prediction of theory that (gamma) and (chi) values are greated enhanced by the occupation number of the f level approaches 1. With substitution of In for Pb, non-monotonic variation of the Neel temperature was found.