EFFECT OF CORRELATED HOPPING ON THE SUPERCONDUCTIVITY OF THE ONE-DIMENSIONAL T-J MODEL

We have studied by exact diagonalization the phase diagram of a ring d escribed by the t-J model supplemented by a next-nearest-neighbor hopp ing combined with a nearest-neighbor spin hip t ''. The sign of t '' i s taken opposite to that derived from a strong-coupling limit of the H ubbard model, and corresponds to that obtained from a systematic low-e nergy reduction of the three-band Hubbard model for CuO2 planes for la rge O-O hopping. We have calculated several correlation functions and the phase diagram. For doping levels realistic for the cuprates, the e ffect of t '' is to shift the region for which superconducting correla tions become dominant, to significantly lower (more realistic) values of J.