Spin-Fluctuation Renormalization of the Temperature of a Superconducting s-Phase in Rare-Earth Intermetallides

A theory of the superconducting state with s-type symmetry of the order parameter ( the transition to this state was observed in recently discovered heavy-fermion skutterudite LaFe4P12) is developed using the periodic Anderson model in the limit of strong electron correlations. Exact representations of Green's functions of the superconducting phase via the normal and anomalous components of the mass and strength operators are obtained. It is shown that an important role in the description of this superconducting phase is played by the anomalous components of the strength operator, which reflect spin-fluctuation processes in the localized subsystem. These components are calculated in the one-loop approximation using the solution of an infinite system of integral equations of self-consistency for the superconducting phase. Numerical calculations show that allowance for the process of scattering on spin fluctuations leads to renormalization of the critical temperature and provides agreement with the experimental data.