Effect of Pressure on Intermediate Valence States in Cerium Kondo Compounds

Electrical resistance, thermal expansion, lattice constants of the intermediate valence materials, α-Ce and CeBe 13, were measured at high pressure. It is found that the Grüneisen parameters of Kondo temperature T K are 13 and 42 for α-Ce and CeBe 13, respectively, and it decreases with increasing pressure. The magnetoresistance of α-Ce shows H2 dependence and its coefficient increases with pressure below 1 GPa, but becomes nearly constant above 1 GPa. The results indicate that the intermediate valence states are enhanced at high pressure indicating the enhancement of hybridization between the 4f electron and conduction band.