Development of high temperature superconducting Josephson junctions and quantum interference devices using low deposition temperature YBa₂Cu₃O_7-x barriers

We have developed Josephson junctions and superconducting quantum interference devices (SQUIDs) in a superconductor-normal-superconductor edge-junction design. These devices are unusual in that we use YBa₂Cu₃O_7-x for both the superconducting and normal layers. The only difference between the layers is the temperature of the substrate during deposition, 695°C for the superconductor and 670°C for the N layer. The lower deposition temperature results in material with a significantly reduced T_c and a higher resistivity. The Josephson junctions produced in this fashion have I_cR_n products typically greater than 100 μV at 77 K. The SQUIDs are not fully optimized but have produced modulation depths of approximately 10 μV at 76 K. These SQUID results are similar to the best results in the literature.