CROSSOVER FROM NON-FERMI-LIQUID TO FERMI-LIQUID BEHAVIOR IN THE MAGNETORESISTIVITY OF U0.9TH0.1BE13

We have measured the temperature T and magnetic field H dependence of the electrical resistivity rho of U0.9Th0.1Be13 in the ranges 0.08 K l ess than or equal to T less than or equal to 10 K and 0 kOe less than or equal to H less than or equal to 80 kOe. In zero applied magnetic f ield below 0.7 K, the resistivity displays a linear temperature depend ence, characteristic of non-Fermi-liquid behavior, down to 0.23 K, whe re it then saturates as T-2, consistent with Fermi-liquid behavior, do wn to 0.08 K, the lowest temperature attained in the experiment. Magne tic fields up to 40 kOe have practically no effect on the electrical r esistivity above 1 K, but dramatically influence the low temperature r ho(T) behavior below 0.7 K. At temperatures below 0.7 K, an anomalousl y large positive magnetoresistivity is accompanied by a rapid expansio n of the temperature region where Fermi-liquid behavior is observed.