Phonon-induced superconductivity in the presence of the charge-density-wave pseudogap. Strong-coupling description

We have considered phonon-induced superconductivity in the presence of the pseudogap originating from Charge-Density-Wave (CDW) excitations within the two-dimensional lattice. Eliashberg formalism has been applied and the CDW effects have been taken into account with the help of the renormalization of propagators in the Dyson equation. The CDW gap has been incorporated in the semiphenomenological way, assuming the d-wave symmetry. We have evaluated the superconducting transition temperature Tc as a function of doping. The influence of the normal-state pseudogap on the isotope shift exponent has also been considered.