Generalized susceptibility and superconductivity in CeMIn5(M=Co,Rh,Ir) and PuCoGa5

Abstract

The band structure, Fermi surface, and generalized susceptibility χ(q) in the constant-matrix-element approximation for the heavy fermion series CeIn3, CeMIn5(M=Co,Rh,Ir), and PuCoGa5 are studied by density functional calculations to address the relationship among superconductivity, magnetism, and Fermi surface nesting in these compounds. Within the scenario of magnetically mediated d wave superconductivity, our results indicate that the behavior of χ(q) of the Ce class materials favors superconductivity if 4f electrons are treated as core states, since it exhibits broad plateaus with large magnitude around q=(0.5,0.5,0) and (0.5, 0.5, 0.5). In contrast, when the 5f electrons are treated as valence electrons, the χ(q) of PuCoGa5 exhibits a very sharp peak at q=(0.5,0.5,0) due to the strong nesting of hole and electron Fermi surface from the 16th and 17th bands. Not only the large spin fluctuation energy but also the strong nesting of Fermi surface in PuCoGa5 may contribute to the much higher Tc than that in the Ce series.