NMR studies of U 0.2 Y 0.8 Pd 3 and YPd 3 at low temperatures

We report results of 89 Y-NMR measurements on U 0.2 Y 0.8 Pd 3 as well as YPd 3 , performed at frequencies between 9 and 16MHz and at temperatures between 0.25 and 2 K. In this temperature range the average Knight shift is +0.5%, temperature-independent and the same for both materials. Also the NMR linewidth for both compounds was found to be temperature and field independent but one order of magnitude larger for U 0.2 Y 0.8 Pd 3 than for YPd 3 . For U 0.2 Y 0.8 Pd 3 our results indicate a distribution of internal static fields at the Y sites and a small temperature-dependent enhancement of the spin-lattice relaxation rate T 1 −1 with respect to YPd 3 . 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. In particular (T 1 T) −1 shows an anomalous temperature dependence.