π-Loops with ds josephson junctions

M. I. Faley* (Corresponding Author), P. Reith, V. S. Stolyarov, I. A. Golovchanskiy, A. A. Golubov, H. Hilgenkamp, R. E. Dunin-Borkowski

*Corresponding author for this work

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Abstract

We fabricated Josephson junctions (JJs) between the d-wave superconductor (SC) YBa 2 Cu 3 O 7 -x (YBCO) and the s-wave SC Nb (ds-JJs) on graphoepitaxially buffered MgO substrates, studied ds-JJs at temperatures down to 30 mK and employed these JJs in π-loops. Current-voltage characteristics of ds-JJs oriented along the [100] axis of YBCO exhibited up to a factor of 200 higher critical current densities than ds-JJs oriented along the [110] axis of YBCO. The critical current I c and the I c R n product of [100]-oriented 3 μm wide ds-JJs are ∼70 μA and ∼200 μV, respectively, at 4.2 K. Rectangular arrays of up to 40 000 π-loops based on such ds-JJs were investigated using a low temperature scanning superconducting quantum interference device (SQUID) microscope. We observed ordering of spontaneously generated half integer magnetic flux quanta in the π-loops correlated with minute spurious background magnetic fields, as well as with configurations and mutual coupling of the π-loops. We manipulated the magnetic states of the π-loops by the local application of magnetic fields using nearby planar coils. This paper paves the way for the use of π-loops in computations that are based on annealing processes.

Original languageEnglish
Article number8606963
JournalIEEE transactions on applied superconductivity
Volume29
Issue number5
Early online date10 Jan 2010
DOIs
Publication statusPublished - 1 Aug 2019

Keywords

  • High-temperature superconductors
  • Josephson junctions
  • quantum computing
  • scanning probe microscopy
  • superconducting quantum interference devices (SQUIDs)

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    Faley, M. I., Reith, P., Stolyarov, V. S., Golovchanskiy, I. A., Golubov, A. A., Hilgenkamp, H., & Dunin-Borkowski, R. E. (2019). π-Loops with ds josephson junctions. IEEE transactions on applied superconductivity, 29(5), [8606963]. https://doi.org/10.1109/TASC.2019.2892078