Properties of Tl2Ba2CaCu2O8 step and bicrystal junctions and dc-SQUIDs on LaAlO3 substrates. / Chen, Y. F.; Ivanov, Z. G.; Stepantsov, E. A.; Tzalenchuk, A. Y.; Zarembinski, S.; Vasiliev, A. L.; Olsson, E.; Yi, H. R.; Claeson, T.; Johansson, L. G.

Applied Superconductivity 1995, Vols. 1 and 2: Vol 1: Plenary Talks and High Current Applications; Vol 2: Small Scale Applications. Vol. 148 1995. p. 1335-1338 (Institute of Physics Conference Series).

Research output: Chapter in Book/Report/Conference proceedingOther contribution

Published
  • Y. F. Chen
  • Z. G. Ivanov
  • E. A. Stepantsov
  • A. Y. Tzalenchuk
  • S. Zarembinski
  • A. L. Vasiliev
  • E. Olsson
  • H. R. Yi
  • T. Claeson
  • L. G. Johansson

Abstract

Step and bicrystal Josephson junctions and de SQUIDs in Tl-2212 epitaxial films have been fabricated and studied. The junctions formed on steps with an angle of 68 degrees have hysteretic multi-branch I-V curves and J(c) approximate to 10(3) A/cm(2) at 4K. TEM images show that Tl-2212 forms an a-axis bar-like grain on the step which is surrounded by c-axis oriented film. However, the supercurrent transport at the step is most likely determined by Josephson tunneling between the Cu-O planes in the c-direction of this grain rather than through the 90 degrees a-axis tilted grain boundaries formed at the step edges. The transport measurements on 32 degrees bicrystal junctions showed that such a grain boundary behaves as a Josephson junction with a J(c) of 6 . 10(3)-2 . 10(4) A/cm(2) while the intragrain J(c) was approximate to 2 . 10(6) A/cm(2), both measured at 77K. The critical temperature of the junctions is in the range 89-108K. The critical current is found to be proportional to (1-T/T-c)(2) at temperatures close to T-c, whereas at low temperatures I-c proportional to 1-T/T-c. The flux noise, S-Phi, of de SQUIDs is measured up to 95K in the locked mode without bias reversing. At 77K the white noise level is 50 mu Phi(0)/root Hz. The crossover frequency to 1/f noise is low, about 5Hz, and the flux noise level at 1 Hz is 440 mu Phi(0)/root Hz.
Original languageEnglish
Title of host publicationApplied Superconductivity 1995, Vols. 1 and 2: Vol 1: Plenary Talks and High Current Applications; Vol 2: Small Scale Applications
Pages1335-1338
Number of pages4
Volume148
Publication statusPublished - 1995

Publication series

NameInstitute of Physics Conference Series

ID: 17060125