Spin fluctuation induced dx2-y2-wave superconductivity in the three-band Hubbard model:: A self-consistent fluctuation-exchange-approximation approach

Using the fluctuation exchange approximation of the three-band Hubbard Hamiltonian we find spin fluctuation induced d(x2-y2)-wave superconductivity with correct order of magnitude of the superconducting transition temperature. This result is obtained for model parameters and for an effective Coulomb interaction which yields normal state scattering rates in agreement with experiments. The chosen parameters of our model give results for the low energy excitations which are similar to those obtained within the effective one-band Hubbard Hamiltonian. We present results for the k dependence of the anomalous self-energy, the spectral density, and for the reduced quasiparticle scattering rate in the superconducting state, where both the copper and oxygen states contribute to superconductivity. Our results are a further strong support for spin fluctuation induced superconductivity and confirm previous effective one-band calculations. [S0163-1829(98)06142-6].