A MICROSCOPIC SCENARIO FOR S-CHANNEL SUPERCONDUCTIVITY IN LAYERED CUPRATES

Two anionic complexes within a cationic lattice frame are the common structural element in all layered cuprate superconductors. One is the extensively investigated current carrying CuO2 layer. It is assumed that the second one creates states near the Fermi level, too, and it is probably quasi-one-dimensional in nature not only for the 1-2-3 and 1-2-4 Y-Ba-Cu phases, but in all hole-doped cuprates, a fact not sufficiently appreciated up to now. The low dimensionally of the doping complex in connection with a strong electron deformation potential at the bridging oxygen may lead to a bipolaronic resonance which is capable of producing s-channel superconductivity as proposed by Friedberg and Lee [1] phenomenologically. Consequences for the temperature dependence of thermodynamic properties as the gap and the upper critical field resulting from a closely related Peierls transition in the chain subsystem are briefly discussed.