Specific heat jump in BCS superconductors
Instituto Nacional de Pesquisas Espaciais, C.P. 515,
S.J. Campos, S.P. 12201-970, Brazil
Published online: 15 March 1999
An exact analytical expression for the specific heat jump at the critical temperature Tc has been obtained directly from the BCS gap equation for any shape of the energy dependent electronic density of states (DOS). We consider a model which takes into consideration electron-electron repulsion, formulated in the Hubbard model along with the electron-electron attraction due to electron-phonon interaction in the BCS formalism. We have analyzed this expression for constant as well as for the Lorentzian forms of DOS. It is shown that the constant DOS in the simple BCS theory cannot explain the large values of , found in some superconductors. The specific heat versus temperature curve has been found to have a peak, similar to that of Eliashberg theory of superconductivity. The influence of repulsive interaction is very small and occurs mainly at higher temperatures.
PACS: 74.20.Fg – BCS theory and its development / 74.20.-z – Theories and models of superconducting state / 74.25.Bt – Thermodynamic properties
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 1999