Theory of Superconductivity in PuCoGa5

Recently, superconductivity in PuCoGa5 was discovered. It has the same crystal structure as CeMIn5(M=Ir, Co, Rh). The electron correlation in PuCoGa5 is estimated to be weak compared with CeMIn5, and the filling number of electrons is considered to be far from 0.5/spin in the band which plays an important role in realizing the superconductivity. Nevertheless, the superconducting transition temperature Tc in PuCoGa5 is almost by an order of magnitude higher than that in CeMIn5. In order to explain the superconductivity with high Tc, we adopt the periodic Anderson model and calculate Tc by solving the Dyson-Gor'kov equation derived by the third order perturbation theory with respect to U. By this calculation, we indicate that the superconducting state of PuCoGa5 is a d-wave pairing state, and show that the good location of two Fermi surfaces results in the high Tc in PuCoGa5.