On the nature of the superconducting gap in the cuprates

Abstract

Recent experiments indicate that the excitation spectrum of the cuprates is characterised, in the superconducting state, by two energy scales: the ``coherence energy'' Δ_c and the ``pseudogap'' Δ_p. Here we consider a simple generalisation of the BCS model that yields exotic pairing and can describe, phenomenologically, the generic trends in the critical temperature T_c of cuprate superconductors. We use the model to predict the gap in the single-particle spectrum arising from the superconductivity and we find evidence that it corresponds to the lower of the two energy scales, Δ_c, seen in the experiments. This supports the view that the origin of the pseudogap is not superconducting fluctuations.

11 pages, including 2 figures. Revised version: corrected typos; improved presentation; some additional discussion; new appendix with main formulae. To appear in J. Phys.: Condens. Matter

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