Transport properties in the system

Abstract

The effect of substitutions in the system has been investigated by means of electrical resistivity and magnetoresistivity measurements. The substitutions of Pd for Ru have been found to (i) suppress a Kondo behaviour at high temperatures, (ii) produce magnetic order and (iii) induce a Kondo-like minimum in the electrical resistivity at low temperatures. We analysed the low-temperature part of the electrical resistivity by considering electron scattering by impurities, by spin-wave excitations and originating from a Kondo effect. Samples with exhibit incoherent Kondo behaviour above about 100 K, while for the 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 system in which a magnetic phase transition from paramagnetic to ferromagnetic and finally to an antiferromagnetic/ferrimagnetic state takes place. A marked difference was found in the magnetoresistivity data for the x = 0.2, 0.6 and 0.8 samples, reflecting a variety of magnetic structures which appear in these compounds.