ALL HIGH-TC JOSEPHSON-JUNCTIONS

Fabrication and characterization of YBa2Cu3O7-YBa2Cu3O7 (YBCO) edge junctions made of two adjacent c-axis oriented epitaxial films separated by a barrier is reported. The advantages of edge geometry are that it yields a small cross section and links, in our case, two YBCO films in their a-b plane which has the longer coherence length. An all in situ process was developed, based on laser ablation deposition of the films and the use of metallic masks. The barrier was formed either by a plasma discharge process or by laser ablation deposition of a thin layer. Additional patterning led to junctions having a typical cross section of about 1 x 20-mu-m2. The junctions were characterized by transport measurements with and without magnetic fields and microwave radiation, and were found to operate at up to 85 K.