ANISOTROPIC SNS JOSEPHSON-JUNCTIONS USING EPITAXIAL YBACUO FILMS

We present the anisotropic Josephson effect in the SNS structures consisting of YBaCuO/Au/Nb film sandwiches, using epitaxial YBaCuO films. SNS junctions with a-b plane orientated YBaCuO films on exhibit the Josephson effect, while no Josephson currents are observed in the junctions with c-axis orientated YBaCuO films. In addition, a-b plane orientated junctions show anisotropic Fraunhofer patterns in the magnetic field dependence of the critical current, depending on the direction of applied magnetic fields. These anisotropic Josephson effects originate from the anisotropy in the coherence length and the magnetic penetration depth of YBaCuO films.