Influence of the structural anisotropy and of the order parameter symmetry on the transport properties of YBa2Cu3O7-delta grain boundaries Josephson junctions

YBa2C3O7-delta artificial grain boundary Josephson junctions have been fabricated by a recently implemented biepitaxial technique, employing MgO and CeO2 as seed layers. The Josephson properties of asymmetric grain boundaries (GBs) characterised by a misalignment of the c-axis (45degrees c-axis tilt or twist) are presented. A comparison with GBs characterised by 45degrees c-axis tilt or twist and by an additional rotation of 45degrees of the a-b planes of one electrode has been also performed. The differences observed in the transport properties have been interpreted in terms Of d(x2-y2) wave symmetry of the order parameter and faceting of the grain boundary. (C) 2002 Elsevier Science B.V. All rights reserved.