EVIDENCE FOR THE KONDO EFFECT AND CROSSOVER IN TRANSPORT BEHAVIOR FOR X-SIMILAR-TO-0.2 OF Y1-XUXPD3

We present measurements of the thermoelectric power S(T) from 2-300 K in the material Y1-xUxPd3, with x = 0, 0.05, 0.1, 0.2, 0.3, and 0.4. The general behavior for x = 0.05, 0.1 is reminiscent of Kondo materials, characterized by a ''giant,'' positive contribution that is linear in T at low temperatures, and is independent of x. This suggests that the Kondo scale is also independent of x, in contrast to the results of other measurements. The high-temperature thermopower changes from positive to negative as x is varied from 0.1 to 0.3, suggestive of a crossover or transition in electronic structure near x = 0.2. The spin-glass transition of the x = 0.3,0.4 alloys is signaled by a zero crossing of S, similar to that observed for conventional spin glasses.