Influence of the structural anisotropy and of the order parameter symmetry on the transport properties of YBa_2Cu_3O_(7-δ) grain boundaries Josephson junctions

摘要

YBa_2C_3O_(7-δ) artificial grain boundary Josephson junctions have been fabricated by a recently implemented biepit-axial technique, employing MgO and CeO_2 as seed layers. The Josephson properties of asymmetric grain boundaries (GBs) characterised by a misalignment of the c-axis (45° c-axis tilt or twist) are presented. A comparison with GBs characterised by 45° c-axis tilt or twist and by an additional rotation of 45° 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_(x~2-y~2) wave symmetry of the order parameter and faceting of the grain boundary.