Properties of high-{ital T}{sub {ital c}} Josephson junctions with Y{sub 0.7}Ca{sub 0.3}Ba{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} barrier layers
- Conductus Inc., 969 West Maude Avenue, Sunnyvale, California 94806 (United States)
We report the use of Y{sub 0.7}Ca{sub 0.3}Ba{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} as an epitaxial barrier between YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} (YBCO) electrodes in high-{ital T}{sub {ital c}} superconductor-normal-superconductor edge junctions. Ca-doped YBCO is an overdoped version of YBCO, and it has an excellent lattice and thermal expansion match with YBCO. We show that these junctions exhibit clean interfaces with resistances smaller than 10{sup {minus}10} {Omega} cm{sup 2}. We present the temperature dependence of the critical current density {ital J}{sub {ital c}} and the junction resistance {ital R}{sub {ital n}} for junctions with 200, 400, and 600 A thick barriers of Y{sub 0.7}Ca{sub 0.3}Ba{sub 2}Cu{sub 3}O{sub 7{minus}{delta}}. As the temperature decreases, the resistance of the junction decreases faster than the resistance calculated from the resistivity of a Y{sub 0.7}Ca{sub 0.3}Ba{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} film. We analyze our data by considering various possibilities for the microstructure in the barrier region. We discuss the ideal conventional proximity effect, diffusion between the barriers and the electrodes, and doping fluctuations inside the barrier. We find that combinations of these ideas explain the observed behavior with reasonable parameters.
- OSTI ID:
- 90513
- Journal Information:
- Physical Review, B: Condensed Matter, Journal Name: Physical Review, B: Condensed Matter Journal Issue: 6 Vol. 52; ISSN PRBMDO; ISSN 0163-1829
- Country of Publication:
- United States
- Language:
- English
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