MoRe/YBCO Josephson junctions and π-loops

M.I. Faley*, P. Reith, C.D. Satrya, V.S. Stolyarov, B. Folkers, A.A. Golubov, H. Hilgenkamp, R.E. Dunin-Borkowski

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

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We have developed Josephson junctions between the d-wave superconductor YBa2Cu3O7-x (YBCO) and the s-wave Mo0.6Re0.4 (MoRe) alloy superconductor (ds-JJs). Such ds Josephson junctions are of interest for superconducting electronics making use of incorporated π-phase shifts. The I(V)-characteristics of the ds-JJs demonstrate a twice larger critical current along the [100] axis of the YBCO film compared to similarly-oriented ds-JJs made with a Nb top electrode. The characteristic voltage I c R n of the YBCO-Au-MoRe ds-JJs is 750 μV at 4.2 K. The ds-JJs that are oriented along the [100] or [010] axes of the YBCO film exhibit a 200 times higher critical current than similar ds-JJs oriented along the [110] axis of the same YBCO film. A critical current density J c = 20 kA cm-2 at 4.2 K was achieved. Different layouts of π-loops based on the novel ds-JJs were arranged in various mutual coupling configurations. Spontaneous persistent currents in the π-loops were investigated using scanning SQUID microscopy. Magnetic states of the π-loops were manipulated by currents in integrated bias lines. Higher flux states up to ±2.5Φ0 were induced and stabilized in the π-loops. Crossover temperatures between thermally activated and quantum tunneling switching processes in the ds-JJs were estimated. The demonstrated ability to stabilise and manipulate states of π-loops paves the way towards new computing concepts such as quantum annealing computing.

Original languageEnglish
Article number044005
JournalSuperconductor science and technology
Issue number4
Publication statusPublished - 1 Apr 2020


  • UT-Hybrid-D
  • Josephson junction
  • scanning SQUID microscopy
  • π-loop
  • D-wave superconductor
  • d-wave superconductor
  • pi-loop


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