PUB - Publikationen an der Universität Bielefeld

We present a microscopic theory for strong spin-fluctuation exchange interaction and an additional electron-phonon interaction alpha2F(q, omega). For an appropriate alpha2F being independent of q we find s-wave superconductivity, whereas for an alpha2F which is strongly suppressed at larger q due to strong electron correlations we find d-wave superconductivity. The resulting spectral weights of the dynamic spin susceptibility are in qualitative agreement with the neutron scattering data obtained on La1.86Sr0.14CuO4 and YBa2Cu3O6.92, respectively. For the d-wave pairing case the electronic thermal conductivity and the low-frequency electrical conductivity exhibit broad, but relatively small peaks below T(c). The quasiparticle relaxation rate decreases rapidly as T drops below T(c), in qualitative agreement with microwave and ultrafast laser measurements on YBCO and BISCO.