PHASE-DIAGRAM IN 2D FROHLICH MODEL OF METAL AT ARBITRARY CARRIERS DENSITY - PSEUDOGAP VERSUS DOPING

It is shown that in 2D system of the fermions with simplest indirect b oson-induced attraction (through the Einstein phonon exchange as an ex ample) along with the normal and superconducting phases there arises a new (called 'abnormal normal' or pseudogap) one where the absolute va lue of the order parameter is finite but its phase is a random quantit y. It is important that this new phase really exists at low carriers d ensity only, i.e. it shrinks when doping increases. The relevance of t he results obtained with dependence of pseudogap on doping in high-tem perature superconductors is speculated. (C) 1998 Elsevier Science B.V.