Non-Phonon Mechanisms of Superconductivity

Abstract

The problem of non-phonon mechanisms of superconductivity is intimately connected with that of critical temperature. When we are dealing with, say, the Josephson effect or electrodynamics, the essential facts are the existence of pairing and the presence of an energy gap. All the relevant formulas involve just the gap; the nature of the pairing mechanism is immaterial. However, the situation is different when we are discussing T _c . It is expressed directly in terms of the parameters of the pairing interaction. For example, this can be seen directly from the BCS expression (Eq. 2.6): it gives T _c in terms of the lattice vibrational frequency and the electron—phonon interaction constant.