Thermodynamics of a retarded d-wave superconductor with resonant impurity scattering

Using a formula for the free energy of an Eliashberg d-wave superconductor, which includes multiple impurity scattering, we study thermodynamic properties. Results are given for two values of the coupling strength between superconducting electrons and antiferromagnetic-spin fluctuations, which are assumed to stabilize the superconductivity. Various impurity-scattering strengths are considered both in the Born approximation and in the unitary limit and a comparison between the two cases is made.