Reentrants-wave superconductivity in the periodic Anderson model with attractive conduction band Hubbard interaction

Spin-flip scattering from magnetic impurities has a strong pair-breaking effect ins-wave superconductors where increasing the concentration of impurities rapidly destroys superconductivity. For small Kondo temperatureT_Kthe destruction of superconductivity is preceded by the reentrant superconductivity at finite temperature rangeT_c2<T<T_c1, while the normal phase reappears atT<T_c2∼T_K. Here we explore the superconducting phase in a periodic system modeled as the Anderson lattice with additional attractive on-site (Hubbard) interactiongacting on the conduction band electrons. We solve the equations using dynamical mean field theory which incorporates Kondo physics, while the pairing interaction is treated on the static mean-field level. For large couplinggwe find reentrant superconductivity which resembles the case with diluted impurities. However, we find evidence that reentrant superconductivity is here not a consequence of many-body correlations leading to the Kondo effect, but it rather stems from a competition between the single-particle hybridization and superconducting pairing. An insight into the spectral functions with in-gap structures is obtained from an approximate noninteracting dual model whose solution interpolates between several exact limits.