Evidence for the Kondo effect and crossover in transport behavior for x~0.2 of Y1-xUxPd3.

Abstract

We present measurements of the thermoelectric power S(T) from 2--300 K in the material ${\mathrm{Y}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{U}}_{\mathit{x}}$${\mathrm{Pd}}_{3}$, 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.