ALL A-AXIS ORIENTED YBA2CU3O7-Y-PRBA2CU3O7-Z-YBA2CU3O7-Y JOSEPHSON DEVICES OPERATING AT 80-K

We have demonstrated the controllable, reproducible fabrication of nonhysteretic Josephson devices with excess-current weak-link characteristics at temperatures up to 80 K. The devices are patterned from in situ deposited alpha-axis oriented YBa2Cu3O7-y-PrBa2Cu3O7 YBa2Cu3O7-y trilayers grown on SrTiO3(001) substrates. Control of the critical current density and resistance is achieved by varying the thickness of the PrBa2Cu3O7 barrier layer. Critical current densities in excess of 10(4) A/cm 2 have been reproducibly measured; good uniformity across the wafer is obtained with device parameters scaling with device area. Strong constant-voltage current steps are observed under 11.2 GHz microwave radiation at temperatures up to and above 80 K.