Fabrication and characterization of 45/spl deg/ a-axis tilt grain boundary YBa/sub 2/Cu/sub 3/O/sub 7-x/ Josephson junctions and dc SQUIDs

YBa/sub 2/Cu/sub 3/O/sub 7/-/sub x/ junctions and dc SQUIDs have been realized by employing 45/spl deg/ a-axis tilt grain boundaries through a fabrication procedure based on the biepitaxial technique. YBa/sub 2/Cu3O/sub 7-x/ grows mainly oriented [103] on SrTiO/sub 3/ and [001] on the MgO seed layer. A wide characterization of the tilt junctions and SQUID properties has been carried out. High values of the I/sub C/R/sub N/ quality factor and of the magnetic flux-to-voltage transfer parameter have been obtained, The observed phenomenology confirms differences from the one typical of 45/spl deg/ c-axis tilt grain boundary junctions and gives important information on the nature of the current steps appearing at finite voltages in the current-voltage characteristics. These devices could also have some impact on experiments designed to study the symmetry of the order parameter, exploiting their microstructure and anisotropic properties. A maximum speed of Josephson vortices as calculated from the voltage step values, of the order of 2 10/sup 6/ m/sec is obtained, which encourages high frequency applications.