Superconductor GdBa₂Cu₃O_7-δ edge junctions with lattice-matched Y_0.6Pr_0.4Ba ₂Cu₃O_7-δ barriers

High-temperature-superconductor Josephson junctions with an edge geometry of superconductor/normal-metal/superconductor have been fabricated on yttria-stabilized zirconia substrates by engineering the electrode and N-layer material to reduce the lattice mismatches (a, b, and c). With GdBa ₂Cu₃O_7-δ as electrodes and Pr-doped Y_0.6Pr_0.4Ba₂Cu₃O _7-δ as a barrier, the lattice mismatches from electrode and barrier layer are reduced to a very low level. The junctions fabricated with such a design demonstrate resistively shunted junction current-voltage characteristics under dc bias at temperatures in the range of 77-88 K. The quite low specific interface resistivity on the order of 10^-10 Ω cm² indicates that the junction performance is controlled by the normal-metal (N) layer material instead of the interfaces. The use of lattice-matched electrode and N-layer material is one of the key design rules to obtain controllable high-temperature superconductor Josephson junctions.