Interlayer coupling in high temperature superconductors

The authors consider the high temperature superconductors such as YBaCuO as a stack of planar superconductors. The interlayer Josephson coupling deduced from the perpendicular penetration depth is of order 10 8 A/cm 2 for YBaCuO and B1SrCaCuO crystals indicates clean limit behavior for in-plane supercurrents but dirty limit behavior for perpendicular supercurrents. The much lower values of transport critical current density J c reported so far are understood in terms of weak pinning for the interplanar vortices as they slide between the planes