THE BOSON-FERMION MODEL OF HIGH-T-C SUPERCONDUCTIVITY DOPING DEPENDENCE

On the basis of well established experimental results we propose a picture for high-T-c superconductivity in which two types of charge carriers play a role: (1) localized bosons in the form of tightly bound electron pairs of polaronic origin and (2) fermions in the form of itinerant valence electrons. The level of the bosons is supposed to fall inside the band of fermions and due to a boson <----> fermion pair-exchange coupling the intrinsically localized bosons can condense and simultaneously induce a BCS-like superconductivity in the fermionic subsystem. We study the doping dependence for this model for such quantities as the critical temperature, the BCS-like gap in the single-particle excitation spectrum of the fermions, the penetration depth and the plasma frequency and compare these results with experiment.