NMR Shift Measurements Of69ga in Unconventional Superconductor PuRhGa5

The NMR shift (K) at the Ga(2) site (the 4i site) has been measured in PuRhGa5, a compound which shows anisotropic superconductivity below T-c approximate to 9 K. In the normal state, K(T) is very nearly independent of T below similar to 30 K. This result is consistent with the relaxation rate measurements. This Korringa-like behavior indicates the formation of Fermi-liquid state below similar to 30 K. The transferred hyperfine coupling constants have been estimated from the relation between K and the bulk susceptibility, showing a strong anisotropy. Measurements of K(T) in the superconducting state have also been performed. A decrease of K in the superconducting state has been observed, which strongly suggests a spin-singlet pairing.