Interplay of magnetism, structure and superconductivity in heavy-fermion systems CeMIn5 and PuMGa5

Experiments that probe the normal and superconducting states of the heavy-fermion compounds CeMIn5, MCo, Rh, Ir, consistently point to the dependence of superconductivity on magnetism and, consequently, to the conclusion that soft magnetic excitations produce Cooper pairing. A more limited number of experiments on the isostructural superconductors PuMGa5, MCo, Rh, also are consistent with a magnetic pairing mechanism, but in these cases, the relationship between magnetism and superconductivity is less obvious. A connection between the Ce- and Pu-based families of unconventional superconductors is provided through a common dependence of their superconducting transition temperatures on lattice anisotropy and a weak structural distortion that may reflect a hybridization-induced change in magnetic fluctuations.