High Pressure Studies of Anomalous Electronic States of Y1 Xuxpd3

The electrical resistivity rho(T) of Y1-xUxPd3 (x = 0, 0.05 and 0.2) and the lattice constants for x = 0 have been measured at high pressure. It is found that the cubic Cu3Au structure is stable up to 12 GPa at room temperature. The Kondo temperature T-K was extracted from the rho(T) curve and it was found that it increases with pressure. A logarithmic temperature dependence characteristic of the Kondo effect was found for x = 0.2 in the temperature range above about 0.5 T-K. Fermi liquid behaviour in rho(T) for x = 0.05, i.e., rho(T) proportional to T-2, is observed and its stability at high pressure is discussed. The pressure dependence of the Kondo temperature T-K is discussed using the Gruneisen parameters at T-K, Gamma(K). It appears that the values Of Gamma(K) are the same for these two compounds (x = 0.05 and 0.2): Gamma(K) = 12. The T-linear behaviour in p(T) for x = 0.2, which is characteristic behaviour for non-Fermi liquids, is collapsed by an application of pressure and typical Fermi liquid quadratic temperature dependence recovers at high pressure. From the result for x = 0.2, the power n of the temperature in rho(T) proportional to T-n is determined as 1.0 at ambient pressure and 1.9 at 5.8 GPa. It is pointed out that the hybridization effect due to the application of pressure gives rise to a crossover from a non-Fermi liquid state to Fermi liquid state. But the crossover temperature T-cr shows a pressure dependence different from that predicted by the two-channel Kondo model.