Spin fluctuation processes in the problem of s-wave superconducting phase of the heavy-fermion intermetallides

Abstract

In the framework of the periodic Anderson model in the limit of strong electron correlations a theory of s-wave superconductivity (this phase has been recently discovered in the skutterudite LaFe4P12) has been developed. The theory is based on kinematic mechanism, provided that the spin fluctuation processes (SFP) are taken into account.To obtain the self-consistent equations for the superconducting phase the diagram technique for Hubbard operators has been used. The exact representations of normal and anomalous Green's functions in terms of normal and anomalous components of mass and strength operators have been obtained. A set of integral equations for superconducting phase was deduced with the assumption that SFP have been accounted for. In the solution of these equations normal and anomalous components of the mass and strength operators have been calculated in the one-loop approximation. Computation has revealed that SFP result in substantial decreasing of critical temperature Tc and shifting the concentration critical point of the superconducting phase transition.