Electron-beam damaged high-temperature superconductor Josephson junctions

Journal Article · Mon Dec 01 04:00:00 EST 1997 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.366422· OSTI ID:552964

Pauza, A J; Booij, W E; Herrmann, K; Moore, D F; Blamire, M G ^[1]; Rudman, D A; Vale, L R ^[2]

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1. IRC in Superconductivity, University of Cambridge, Madingley Road, Cambridge CB3 0HE (United Kingdom)
2. National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80303-3328 (United States)

Results are presented on the fabrication and characterization of high critical temperature Josephson junctions in thin films of YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} produced by the process of focused electron-beam irradiation using 350 keV electrons. The junctions so produced have uniform spatial current densities, can be described in terms of the resistive shunted junction model, and their current densities can be tailored for a given operating temperature. The physical properties of the damaged barrier can be described as a superconducting material of either reduced or zero critical temperature (T{sub c}), which has a length of {approximately}15nm. The T{sub c} reduction is caused primarily by oxygen Frenkel defects in the Cu{endash}O planes. The large beam currents used in the fabrication of the junctions mean that the extent of the barrier is limited by the incident electron-beam diameter, rather than by scattering within the film. The properties of the barrier can be calculated using a superconductor/normal/superconductor (SNS) junction model with no boundary resistance. From the SNS model, we can predict the scaling of the critical current{endash}resistance (I{sub c}R{sub n}) product and gain insight into the factors controlling the junction properties, T{sub c}, and reproducibility. From the measured I{sub c}R{sub n} scaling data, we can predict the I{sub c}R{sub n} product of a junction at a given operating temperature with a given current density. I{sub c}R{sub n} products of {approximately}2mV can be achieved at 4.2 K. The reproducibility of several junctions in a number of samples can be characterized by the ratio of the maximum-to-minimum critical currents on the same substrate of less than 1.4. Stability over several months has been demonstrated at room and refrigerator temperatures (297 and 281 K) for junctions that have been initially over damaged and then annealed at temperatures {approximately}380K. (Abstract Truncated)

• OSTI ID: 552964
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 11 Vol. 82; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BARIUM COMPOUNDS
BARIUM OXIDES
COPPER OXIDES
CURRENT DENSITY
ELECTRON BEAMS
FRENKEL DEFECTS
HIGH-TC SUPERCONDUCTORS
JOSEPHSON JUNCTIONS
KEV RANGE 100-1000
RADIATION EFFECTS
YTTRIUM COMPOUNDS
YTTRIUM OXIDES