Nuclear magnetic resonance studies of non-Fermi liquid behaviour in Y0.8UxTh0.2-xPd3 and Y0.95U0.05Pd3

Y-89 NMR spectra of the non-Fermi liquid alloys Y0.8UxTh0.2-xPd3, x = 0, 0.01, 0.025, and 0.05, exhibit resolved impurity satellites due to specific configurations of U impurities around Y sites. The strongly concentration-dependent satellite linewidths grow more rapidly than the satellite shifts as temperature is reduced, indicating a distribution of characteristic temperatures and the influence of interactions between U ions. The data suggest a disorder-driven mechanism for non-Fermi liquid behavior in this system. The concentration-independent satellite shifts from the bulk resonance are not proportional to the macroscopic magnetic susceptibility, suggesting an unconventional Kondo effect. Y-89 NMR spectra of the related non-Fermi liquid alloy Y0.95U0.05Pd3 also exhibit resolved impurity satellites, the behavior of which gives no indication of widely distributed characteristic temperatures. This suggests that ligand disorder is more important than f-sublattice dilution in driving non-Fermi liquid behavior in Y0.8UxTh0.2-xPd3. (C) 2001 Elsevier Science B.V. All rights reserved.