Correlation of current-voltage characteristics of step-edge YBa2Cu3O7 Josephson junctions with the step angle

K. Herrmann; Michael Siegel; Gerhard Kunkel; A. Thust; B. Kabius; C. L. Jia; Juergen Schubert; Alex I. Braginski

doi:10.1117/12.181010

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2 July 1994 Correlation of current-voltage characteristics of step-edge YBa₂Cu₃O₇ Josephson junctions with the step angle

K. Herrmann, Michael Siegel, Gerhard Kunkel, A. Thust, B. Kabius, C. L. Jia, Juergen Schubert, Alex I. Braginski

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Proceedings Volume 2160, Superconductive Devices and Circuits; (1994) https://doi.org/10.1117/12.181010
Event: OE/LASE '94, 1994, Los Angeles, CA, United States

Abstract

We report on a systematic study of the transport characteristics of YBa₂Cu₃O₇ (YBCO) step-edge Josephson junctions as a function of the step angle. The microstructure of a YBCO film depends very critically on the step angle (alpha) in a SrTiO₃ or LaAlO₃ substrate. Briefly, on shallow steps (0 < (alpha) < 44 degree(s)) the film grows epitaxially across the step. On steep steps (46 degree(s) < (alpha) < 85 degree(s)) two grain boundaries occur on the step. In this paper it is shown that the I-V curves of the step-edge junction reflect the microstructure of the YBCO film on the step. The I-V curves on shallow steps are of flux-flow type. On 45 degree(s) steps there are several Josephson junctions with different critical currents, while on steep steps two critical currents are found in the I-V curve. Summarizing all data, we conclude that the grain boundaries formed on steep steps are responsible for the Josephson behaviour of the junctions.

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K. Herrmann, Michael Siegel, Gerhard Kunkel, A. Thust, B. Kabius, C. L. Jia, Juergen Schubert, and Alex I. Braginski "Correlation of current-voltage characteristics of step-edge YBa₂Cu₃O₇ Josephson junctions with the step angle", Proc. SPIE 2160, Superconductive Devices and Circuits, (2 July 1994); https://doi.org/10.1117/12.181010

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