SELF-CONSISTENT CALCULATION OF SPIN FLUCTUATIONS FOR THE 2-DIMENSIONAL HUBBARD-MODEL AND ADDITIONAL HIGH-T(C) PAIRING INTERACTION

The momentum, energy, and temperature dependence of the dynamic spin susceptibility is calculated self-consistently for the two-dimensional Hubbard model with additional electron-phonon interaction. The spin-fluctuation spectral density considered as a function of momentum exhibits four incommensurate peaks and a local minimum at the zone edge of the Brillouin zone. The large self-energy corrections tend to smooth out the peak and gap structure of the spin fluctuation spectral density. In the presence of an electron-phonon interaction (lambda(ph)eff almost-equal-to 2.2, U/t 2.3) a transition temperature T(c) = 84 K is-found for s-wave pairing. Above T(c) the incommensurate peak and gap structure seen in a momentum scan is strongly smoothed out, and for increasing temperature and energy, the two well-separated peaks evolve into a single broad peak at the zone edge. For lower energies the whole structure is rapidly suppressed as the temperature drops below T(c). The results for the resistivity, the nuclear-spin relaxation rate, and the neutron-scattering spectral weight are compared with experimental data on La2-xSrxCuO4 and YBa2Cu3O7-x.