TRANSPORT-PROPERTIES IN THE URU1-XPDXGA SYSTEM

The effect of substitutions in the URu1-xPdxGa system has been investi gated by means of electrical resistivity and magnetoresistivity measur ements. The substitutions of Pd for Ru have been found to (i) suppress a Kondo behaviour at high temperatures, (ii) produce magnetic order a nd (iii) induce a Kondo-like minimum in the electrical resistivity at low temperatures. We analysed the low-temperature part of the electric al resistivity by considering electron scattering by impurities, by sp in-wave excitations and originating from a Kondo effect. Samples with 0 less than or equal to x less than or equal to 0.3 exhibit incoherent Kondo behaviour above about 100 K, while for the 0.4 less than or equ al to x less than or equal to 0.8 compositions a broad maximum appears in the resistivity around 150-180 K, presumably due to a combination of the Kondo and crystal-field effects. The magnetoresistivity results support the earlier proposal derived from the magnetic studies of the URu1-xPdxGa system in which a magnetic phase transition from paramagn etic to ferromagnetic and finally to an antiferromagnetic/ferrimagneti c state takes place. A marked difference was found in the magnetoresis tivity data for the x = 0.2, 0.6 and 0.8 samples, reflecting a variety of magnetic structures which appear in these compounds.