NMR studies of two unusual f-electron metals

We present the results of nuclear magnetic resonance (NMR) studies down to very low temperatures for two U compounds, UCu3.5Pd1.5 and U0.8Y0.2Pd3, where the conduction electrons experience strong interactions and for which the temperature dependences of the thermal and transport properties do not obey the expectations of a simple Fermi-liquid model. Also the temperature and field dependences of the nuclear magnetization recovery of UCu3.5Pd1.5 in Cu nuclear quadrupole resonance show unusual features that cannot be reconciled with common expectations for a simple metal, but they are well accounted for by the Kondo disorder model. For U0.8Y0.2Pd3, our Y NMR results indicate a distribution of internal static magnetic fields at the Y sites and a small temperature-dependent enhancement of the spin-lattice relaxation rateT1− with respect to YPd3. The NMR spectra are consistent with the presence of very small frozen U moments, but the temperature dependence of the spin-lattice relaxation rate indicates a more complicated situation.