OBSERVATION OF PD-105 NMR AND NQR SIGNALS IN THE HEAVY-FERMION SUPERCONDUCTOR UPD2AL3

Pd-105 NMR and NQR measurements have been performed both in the normal and in the superconducting states for the heavy-fermion superconducto r UPd2Al3. The magnitude of the internal field at Pd is found to be ab out 3 kOe (at 4.2 K) in the antiferromagnetically (AF) ordered state. The nuclear spin-lattice relaxation rate, 1/T-1, in UPd2Al3 is nearly temperature, T, independent in the paramagnetic state up to 60 K, succ essively diverges at Neel temperature associated with the critical slo wing down of U magnetic moments, and then decreases markedly in the AF ordered state, which is well explained by a localized moment picture. These results have shown that Pd atoms are nonmagnetic, in which 4d e lectrons couple very weakly to U moments. In the superconducting state , 1/T-1 decreases in proportion to T-3 down to 0.5 K with no coherence peak just below T-C, which indicates the occurrence of anisotropic su perconductivity having line nodes in the superconducting energy gap. T he coexistence of the AF ordering and the anisotropic superconductivit y in UPd2Al3 could unambiguously be confirmed.