Al-27 impurity-satellite NMR and non-Fermi-liquid behavior in U1-xThxPd2Al3

Non-Fermi-liquid (NFL) behavior in the f-sublattice-diluted alloy system U1 -xThxPd2Al3 has been studied using Al-27 nuclear magnetic resonance. Impuri ty satellites due to specific U near-neighbor configurations to Al-27 sites are clearly resolved in both random and field-aligned powder samples. The particular configuration associated with each satellite is identified by co mparison of calculated and observed satellite intensities. The spatial mean (K) over bar and rms spread delta K of impurity satellite shifts, which ar e related to the mean <(chi)over bar> and rms spread delta chi of the inhom ogeneous susceptibility, have been measured in field-aligned powders with t he crystalline c axis both perpendicular and parallel to the external field . Satellites corresponding to only one uranium near neighbor were chosen fo r analysis, since in this case delta chi(T)/chi(T) = delta K/(K) over bar i ndependent of the (unknown) spatial correlation of the random susceptibilit y inhomogeneity. The relatively narrow lines observed at low temperatures s uggest that disorder-induced inhomogeneity of the f-ion-conduction-electron hybridization is not the cause of NFL behavior in these alloys: at low tem peratures the experimental values of delta chi(T)/chi(T) are much smaller t han required by disorder-driven models. This is in contrast to results in a t least some alloys with disordered non-f-ion nearest neighbors to f ions ( ''ligand disorder''), where disorder-driven theories give good accounts of NFL behavior. Our results suggest that f-ion dilution does not produce as m uch inhomogeneity of the hybridization strength as substitution on ligand s ites.