Charge-density-wave pseudogap and two-dimensional superconductivity within strong-coupling description

We have considered the role of charge-density-pseudogap for phonon-mediated superconductivity on two-dimensional lattice. The propagators that enter generalized Eliashberg equations have been renormalized to account for quasi-particle energies related to the formation of the pseudogap, which has been assumed to be of d-wave symmetry. We have evaluated the superconducting transition temperature T-c as a function of doping. It occurs that T-c for d-wave symmetry well reflects experimental behavior. Our results for the isotope shift exponent alpha show that at low doping, the presence of the pseudogap may contribute to alpha > 1/2 as well as to alpha < 1/2 values.