A PAIRING MECHANISM IN SUPERCONDUCTIVITY DUE TO THE SCREENED COULOMB FIELD

It is the purpose of this note to attempt to develop a new concept for the superconducting Cooper-pairing instability based on the considera tion of pair interactions in the particle-hole channel of an interacti ng Fermi gas. This concept is an extension of the conventional Cooper instability and may lead to a unified understanding of both low- and h igh-T-c superconductivity. Pairing of two quasiparticles is analogous to the resonating valence binding (RVB) between two electrons in a pos itronium molecule-like structure (biexciton). The possible scattering diagrams from this model allow one to evaluate the vertex part Gamma(c ) in the charge channel. T-c is calculated using the pole condition of Gamma(c). It has been found that T-c can reach quite high values and gives rise to the bell shape. T-c depends on the carrier density, inte rlayer distance, dieletric constant and electron band mass. (C) 1997 A cademic Press Limited