PUB - Publikationen an der Universität Bielefeld

The eigenvalues of the superconducting states of the three-band Hubbard model are calculated as functions of band-filling n, on-site repulsion U, and Cu-O repulsion V. We take full into account the momentum and energy dependence of the pairing interaction due to exchange of spin and charge fluctuations. Near the spin-density-wave instability the leading eigenvalue is that of the pairing state with d(x)2(-y)2 symmetry. This eigenvalue, lambda(d), increases rapidly and passes through unity as V is increased towards the charge-density-wave instability. The superconducting order parameter phi(d)(($) over right arrow k,omega) shows a ($) over right arrow k-dependence which deviates substantially from the simplest form cos (pi k(x)) - cos (pi k(y)), and Im phi(d)(($) over right arrow k,omega) exhibits a large and narrow peak as function of omega at the characteristic energy of the spin fluctuation mode.