NON-FERMI-LIQUID SCALING OF THE MAGNETIC RESPONSE IN UCU5-XPDX (X=1,1.5)

We have determined the magnetic response S(omega) of UCu5-xPdx (x = 1, 1.5) for temperatures T ranging from 12 to 300 K and energy transfers omega from 0.5 to 200 meV. S(omega) is virtually identical in the two compounds, displaying localized moment dynamics for omega greater than or similar to 25 meV. For omega < 25 meV, temperature provides the only energy scale for the magnetic excitations with the dynamical susceptibility described by a universal scaling function chi''(omega,T) similar to omega-(1/3)Z(omega/T). We argue that S(omega) represents critical scattering associated with a T=0 phase transition, whose origin lies with the magnetic screening of individual uranium ions.