Observation ofPd105NMR and NQR signals in the heavy-fermion superconductorUPd2Al3

${}_{}{}^{105}{}_{}{}^{}\mathrm{Pd}$ NMR and NQR measurements have been performed both in the normal and in the superconducting states for the heavy-fermion superconductor ${\mathrm{UPd}}_2$ ${\mathrm{Al}}_3$. The magnitude of the internal field at Pd is found to be about 3 kOe (at 4.2 K) in the antiferromagnetically (AF) ordered state. The nuclear spin-lattice relaxation rate, 1/${\mathrm{T}}_1$, in ${\mathrm{UPd}}_2$ ${\mathrm{Al}}_3$ is nearly temperature, T, independent in the paramagnetic state up to 60 K, successively diverges at Néel temperature associated with the critical slowing 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 electrons couple very weakly to U moments. In the superconducting state, 1/${\mathrm{T}}_1$ decreases in proportion to ${\mathrm{T}}^3$ down to 0.5 K with no coherence peak just below ${\mathrm{T}}_{\mathrm{C}}$, which indicates the occurrence of anisotropic superconductivity having line nodes in the superconducting energy gap. The coexistence of the AF ordering and the anisotropic superconductivity in ${\mathrm{UPd}}_2$ ${\mathrm{Al}}_3$ could unambiguously be confirmed.