POSSIBLE MARGINALITY OF THE SUPERCONDUCTING GAP SYMMETRY IN THE OXIDES

It is pointed out that in systems having the electronic topology of hi gh-T-c cuprate superconductors, isotropic s-wave electron-boson intera ction in the momentum decoupling regime leads to either s or d-wave su perconductivity depending on the conventional values of the Coulomb ps eudopotential. Different high-T-c oxides may naturally have different gap symmetries having nevertheless the same pairing interaction and si milar T(c)s. A new type of first order phase transition from s-wave to d-wave superconductivity (and vice-versa) is possible by adjusting th e doping, in accordance with puzzling photoemission and Raman results where a transition from d-wave to s-wave is reported Bi2Sr2CaCu2O8 by overdoping. (C) 1998 Elsevier Science Ltd. All rights reserved.