Gap and subgap tunnelling in cuprates

E-ISSN： 1286-4854|54|3|373-379

ISSN： 0295-5075

Source： EPL (EUROPHYSICS LETTERS), Vol.54, Iss.3, 2010-03, pp. : 373-379

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Abstract

We describe strongly attractive carriers in cuprates in theframework of a simple quasi-one-dimensional Hamiltonian with alocal attraction. In contrast with the conventional BCS theory,there are two energy scales, a temperature-independent incoherentgap $\Delta_\ab{p}$ and a temperature-dependent coherent gap$\Delta_\ab{c} (T)$ combining into one temperature-dependent global gap$\Delta=(\Delta_\ab{p}^2 +\Delta_\ab{c}^2)^{1/2}$.The temperature dependence of the gap and single-particle (Giaver)tunnelling spectra in cuprates are quantitatively described. Twodistinct energy scales observed in Giaver tunnelling andelectron-hole reflection experiments are understood and their linkwith the zero-bias conductance peak and the symmetry of the orderparameter is discussed.