Anisotropy effects on the specific heat jump of a superconductor with normal and paramagnetic impurities

Abstract

We present analytical calculations of the specific heat jump of an anisotropic superconductor with normal and paramagnetic impurities. We solve the imaginary-axis Eliashberg equations with a square-well model for the electron-phonon interaction and obtain additional terms not present in BCS theory. For low concentrations of paramagnetic impurities, anisotropy decreases the specific heat jump normalized to the normal state specific heat, while this quantity is larger in the anisotropic superconductor than in the isotropic one for large enough concentrations of paramagnetic impurities.