Magnetic scaling of non-Fermi-liquid UCu5-xPdx (x=0.8, 0.9, 1, 1.2)

The UCu5-xPdx heavy-fermion alloy system is known to exhibit non-Fermi-liquid (NFL) behaviour for compositions with x approximate to 1. The magnetic properties associated with Nn behaviour of this system are the focus of this study. Results are presented on the temperature (1.7 less than or equal to T less than or equal to 300 K) and magnetic field (0 less than or equal to B less than or equal to 5 T) dependences of the magnetization M and susceptibility chi for polycrystalline UCu5-xPdx samples with x = 0.8, 0.9, 1.0 and 1.2. We emphasize the observed field dependence of chi at low temperatures and illustrate the instability of NFL properties against magnetic field. Our K (T) data present a systematic power-law divergence for NFL UCu5-xPdx at low temperatures in the limit of small measuring fields. This is interpreted in terms of Griffiths-phase singularities near a quantum critical point which are treated in a model given by Castro Neto and co-workers that includes the effects of structural disorder and a generic RKKY-Kondo interplay (where RKKY = Ruderman-Kittel-Kasuya-Yosida). For the extended range 1.7 less than or equal to T less than or equal to 300 K, we find that chi (T) scales reasonably well with a theoretical expectation of Souletie and co-workers of Nn behaviour of Kondo systems. Finally, our M(T, B) data for magnetic fields up to 5 T and 1.7 less than or equal to T less than or equal to 21 K are shown to conform to a Nn scaling relation that applies to T = 0 quantum critical systems. The above analyses support the role that magnetic interactions are thought to play in Nn UCu5-xPdx.