High-Tc interferometers using all YBa2Cu3O7-δ trilayer junctions

We have demonstrated high-T-c interferometers using YBaCuO trilayer junctions, which are two-junction-type interferometers with a direct current injection. In order to realize a small loop inductance value without a ground plane, the interferometers were designed to have loop inductance with a vertical stacked structure by overlapping junction bridges on base electrodes. The interferometers showed clear threshold characteristics in the control current dependence of the gate current at temperatures below 70 K. The temperature dependence of the loop inductance showed good agreement with a calculation result based on a strip-line model. The sheet inductance was estimated to be 0.85 pH/square at 4.2 K from the threshold characteristics of the interferometers by changing the bridge length between the two junctions, which was in good agreement with the design value. (C) 2003 American Institute of Physics.