Slope of specific-heat jump at Tc in a very-strong-coupling superconductor

R. Akis; F. Marsiglio; J. P. Carbotte

doi:10.1103/PhysRevB.39.2722

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Slope of specific-heat jump at Tc in a very-strong-coupling superconductor

R. Akis, F. Marsiglio, J. P. Carbotte

DOI 10.1103/PhysRevB.39.2722 · Physical Review B

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Abstract

We have calculated the normalized slope of the specific heat at the critical temperature Tc as a function of coupling strength. As the coupling is increased the slope first increases rapidly from its Bardeen-Cooper-Schrieffer value of 2.63, reaches a maximum, and then decreases as we reach the very-strong-coupling regime. Using a δ-function spectral density, a local maximum is established which must be satisfied by any Eliashberg superconductor. Comparison with a recent experiment indicates a serious violation of this bound which, if confirmed, implies that some important modification of the theory is required.