Feasibility of biepitaxial YBa₂Cu₃O_7-x Josephson junctions for fundamental studies and potential circuit implementation

We present various concepts and experimental procedures to produce biepitaxial YBa2Cu3O7-x grain-boundary Josephson junctions. The device properties have an interesting phenomenology, related in part to the possible influence of "π loops." The performance of our junctions and superconducting quantum interference devices indicates significant improvement in the biepitaxial technique. Further, we propose methods for fabricating circuits in which 0 and π loops are controllably located on the same chip.