Superconductivity and incommensurate spin fluctuations in a generalized t-J model for the cuprates

Abstract

We consider the slave-fermion Schwinger-boson decomposition of an effective\nmodel obtained through a systematic low-energy reduction of the three-band\nHubbard Hamiltonian. The model includes a three-site term t'' similar to that\nobtained in the large-U limit of the Hubbard model but of opposite sign for\nrealistic or large O-O hopping. For parameters close to the most realistic ones\nfor the cuprates, the mean-field solution exhibits d+s superconductivity\n(predominantly d_{x^2-y^2}) with a dependence on doping x very similar to the\nexperimentally observed. We also obtained incommensurate peaks at wave vectors\nnear $\\pi (1,1 +(-) 2x)$ in the spin structure factor, which also agree with\nexperiment.\n