Thermodynamics of superconductors with charge- and spin-density waves

Using thermal Green's function technique the thermodynamics of superconductors with charge- and spin-density waves is considered. The Δ/Tc ratio and the paramagnetic limit Hp are calculated for various values of the dielectric gap Σ and the parameter ν = Nnd(0)/Nd(0), where Nnd(0) and Nd(0) are the electron densities of states for non-dielectrized and dielectrized Fermi surface sections, Δ(0) is the zero-temperature value of the superconducting order parameters, and Tc is the critical temperature. It is shown that for the charge-density wave-superconductors the values Δ(0)/Tc are substantially less than in the conventional BCS theory. The theoretical conclusions are in a good agreement with the experiment. (author)