Feasibility of biepitaxial YBa2Cu3O7-x Josephson junctions for fundamentalstudies and potential circuit implementation

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