Gap and subgap tunnelling in cuprates
Department of Physics, Loughborough University
Loughborough LE11 3TU, UK
2 P.L. Kapitza Institute for Physical Problems Kosygin st. 2, 117973 Moscow, GSP-1, Russia
Accepted: 19 February 2001
We describe strongly attractive carriers in cuprates in the framework of a simple quasi-one-dimensional Hamiltonian with a local attraction. In contrast with the conventional BCS theory, there are two energy scales, a temperature-independent incoherent gap and a temperature-dependent coherent gap combining into one temperature-dependent global gap . The temperature dependence of the gap and single-particle (Giaver) tunnelling spectra in cuprates are quantitatively described. Two distinct energy scales observed in Giaver tunnelling and electron-hole reflection experiments are understood and their link with the zero-bias conductance peak and the symmetry of the order parameter is discussed.
PACS: 74.20.-z – Theories and models of superconducting state / 74.20.Mn – Nonconventional mechanisms (spin fluctuations, polarons and bipolarons, resonating valence bond model, anyon mechanism, marginal Fermi liquid, Luttinger liquid, etc.) / 74.50.+r – Proximity effects, weak links, tunneling phenomena, and Josephson effects
© EDP Sciences, 2001