JOSEPHSON EFFECTS ON YBA2CU3OY JUNCTIONS AND SQUID

Characteristics of YBa2Cu3Oy step-edge and bi-epitaxial Josephson junc tions and SQUID's are reported. Current-voltage (I - V) curves show th e behavior predicted according to a model of a resistively shunted jun ction (RSJ). The I - V curves under microwave irradiation show constan t, voltage steps; the amplitude of the constant voltage steps is modul ated by the microwave power. The RSJ current-source model is used to d iscuss the I - V curves under microwave irradiation and applied magnet ic fields. The V - Phi curves of the SQUID's show modulation up to 77 K.