Two Channel Kondo Effect and Superconductivity in Pu and Np compounds

Recently, superconductivity has been observed in two heavy fermion compounds, PuCoGa$_5$ and NpPd$_5$Al$_2$, which transition directly from unquenched spins into the superconducting state, without passing through an intermediate heavy fermi liquid. These two compounds can be modeled with the two channel Kondo model, where the two channels derive from virtual valence fluctuations of different crystal symmetries. The electron-spin scattering develops an Andreev component, creating a composite bound state of a spin-flip and a triplet pair of electrons. This process can be examined in a controlled fashion with symplectic N, with the maximum transition temperature occuring when the two channels have equal strengths. We will also discuss the effect of Pu doping on the superconducting transition temperature of NpPd$_5$Al$_2$.