Muon spill rotation and non-Fermi liquid behavior in UCu4Pd

Muon spin rotation and relaxation (mu SR) experiments have been carried out on the non-Fermi liquid (NFL) heavy-fermion compound UCu4Pd. Transverse-fi eld mu SR line widths indicate that the U-ion susceptibility is inhomogeneo us and in good agreement with predictions of disorder-driven NFL mechanisms . The inhomogeneity seems to be remarkably independent of the exact amount of structural disorder. Longitudinal-field experiments yield muon spin-latt ice relaxation rates which are two orders of magnitude faster than estimate s from a single-ion 'Kondo disorder' model. This suggests a cooperative rat her than a single-ion NFL mechanism. No evidence is found for freezing of m ore than a few percent of U-ion moments in UCu4Pd above 100 mK. (C) 2000 El sevier Science B.V. All rights reserved.