OBSERVATION OF JOSEPHSON EFFECT IN YBA2CU3O7-X ND1.85CE0.15CUO4-Y BILAYER JUNCTIONS/

Josephson junctions were fabricated at the interface of YBa2Cu3O7-x (Y BCO) and Nd1.85Ce0.15CuO4-y (NCCO) in heteroepitaxially grown supercon ducting bilayers. Devices of various configurations and sizes were fab ricated, and they display a resistively shunted junction like I-V char acteristics with hysteresis at low temperatures. A clear ac Josephson effect was observed under microwave irradiation, and critical currents were completely suppressible by external magnetic fields. Oxygen diff usion or charge diffusion at the interface are possible origins for th e barrier formation. (C) 1995 American Institute of Physics.