Unconventional superconductivity in PuCoGa5PuCoGa5

We report nuclear magnetic resonance (NMR) data in the new heavy fermion superconductor PuCoGa5PuCoGa5 (Tc=18.5K) in the normal and superconducting states. Measurements of the Knight shift and the nuclear spin lattice relaxation rate in the superconducting state show a spin-singlet with lines of nodes in the gap function, and our calculations indicate that the data are consistent with a strong-coupling d-wave gap function with Δ/kBTc=4Δ/kBTc=4. In the normal state, the temperature dependence of the spin lattice relaxation rate suggests the presence of antiferromagnetic correlations, and scales with TcTc in the same manner as in other heavy fermion superconductors, as well as the high-temperature superconductor, YBa2Cu3O7YBa2Cu3O7.