Electronic theory for bilayer effects in high-T-c superconductors

The normal and superconducting state of two coupled CuO2 layers in the high-ir, superconductors are investigated by using the bilayer Hubbard model, the fluctuation exchange approximation on the real frequency axis, and the Eliashberg theory. We find that the planes are antiferromagnetically correlated leading to a strongly enhanced shadow band formation. Furthermore, the interlayer hopping is renormalized which causes a blocking of the interplane charge transfer for low doping. Finally, the superconducting order parameter has a d(x)2-(y)2 symmetry with significant interlayer contributions and a larger optimal doping with respect to the single layer.