Effect of hybridization on the specific heat jump in two-band superconductors

Abstract

We study the effect of a constant hybridization V 0 in the specific heat jump Δ C at the superconducting critical temperature T c, dealing with an exact analytical expression obtained from the extended BCS gap equation. Our model is suitable to discuss a superconducting material described by a hybridized two-band model, within an extended BCS approach. In this Hubbard like model, we assume that the electron–electron repulsion U r and attractive electron–“phonon” interaction U a, both occur at the narrow d-band. One observes that: (i) the ratio α of the effective band masses in a homothetic band picture plays an important role in the jump, and (ii) the Hubbard like repulsive interaction is very small and plays no significant role in the range of temperatures where superconductivity occurs.