Superconductor{endash}normal{endash}superconductor step-edge junctions with Au barriers
- Institut fuer Schicht- und Ionentechnik, Forschungszentrum Juelich GmbH, 52425 Juelich (Germany)
YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} superconductor{endash}normal{endash}superconductor junctions in step-edge geometry are fabricated by an {ital in} {ital situ} process using off-axis sputter deposition. Gold is used as the normal metal interlayer. A special inhibiting layer is introduced to ensure proper separation of the superconducting electrodes. The temperature dependence of the critical current {ital I}{sub {ital c}} is nearly linear. The junctions show high normal resistances up to {ital R}{sub {ital N}}=10 {Omega} and high {ital I}{sub {ital c}}{ital R}{sub {ital N}} products up to 8.8 mV at 4.2 K. {ital I}{endash}{ital V} characteristics exhibit a large excess current {ital I}{sub ex} over the whole temperature range, even for electrically narrow junctions. The power dependence of Shapiro step heights shows characteristic deviations from the resistively and capacitively shunted junction model. Calculations using the time-dependent Ginzburg{endash}Landau equations are carried out to model the measured {ital I}{endash}{ital V} characteristics with and without microwave irradiation. A point-contact-like superconductor{endash}constriction{endash}superconductor model is suggested to explain the excess current and the measured temperature dependence of {ital I}{sub {ital c}} and {ital I}{sub ex}. Time-dependent Ginzburg{endash}Landau equations are used to account for the observed dynamic characteristics. {copyright} {ital 1996 American Institute of Physics.}
- OSTI ID:
- 389268
- Journal Information:
- Journal of Applied Physics, Vol. 80, Issue 11; Other Information: PBD: Dec 1996
- Country of Publication:
- United States
- Language:
- English
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