De Haas - Van Alphen effect and Fermi surface properties in U _1-xTh_xPd₃ alloys

We report the first observation of the de Haas-van Alphen (dHvA) oscillations in U-based alloys U_1-xTh_xPd₃ up to x 0.5. In U_0.5Th_0.5Pd₃, the dHvA oscillations β₂ can be observed in the (1100) plane and the frequencies of the oscillations as well as their angular dependences are found to be nearly the same as those in UPd₃. On the other hand, the effective mass of the β₂ oscillation is found to decrease with x from 1.78m ₀ of UPd₃ to 1.32m₀ of U_0.5Th _0.5Pd₃. From these observations we argue that the f electrons in UPd₃ are nearly localized and the interactions between the f electrons and the conduction electrons are weak.