Non-Fermi-liquid scaling of the magnetic response in UCu5-xPdx(x=1,1.5)

We have determined the magnetic response S(ω) of UCu5-xPdx(x=1,1.5) for temperatures T ranging from 12 to 300 K and energy transfers ω from 0.5 to 200 meV. S(ω) is virtually identical in the two compounds, displaying localized moment dynamics for ω approx-gt 25 meV. For ω<25 meV, temperature provides the only energy scale for the magnetic excitations with the dynamical susceptibility described by a universal scaling function χ double-prime(ω,T)∼ω-1/3Z(ω/T). We argue that S(ω) represents critical scattering associated with a T=0 phase transition, whose origin lies with the magnetic screening of individual uranium ions