Theory of the persistent superconducting diode effect in twisted high-T<sub>c</sub> cuprates

ORAL

Abstract

C-axis Josephson junctions fabricated from Bi2Sr2CaCu2O8+δ flakes twisted near 45° exhibit superconducting diode effect with a well-defined polarity which persists even after the sample has been cycled through the normal phase by raising its temperature or by exceeding its critical current. This observation suggests that time-reversal symmetry in these twisted flakes is broken not only below Tc, as suggested by existing theoretical work which predicts a chiral d+id' phase, but also in the normal state. We present here a symmetry-based phenomenological framework that explains the observed properties of such junctions with a minimal number of assumptions. Our model postulates an extra Ising order parameter that is linearly coupled to the superconducting chirality and remains ordered in the normal state -- thus providing the mechanism for the memory effect that underlies the fixed diode polarity. We show that, remarkably, this coupling is only symmetry-allowed in twisted junctions; at zero twist it vanishes in accord with the large body of experimental data indicating that untwisted optimally doped cuprates are non-magnetic.

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Presenters

  • Marcel Franz

    • University of British Columbia

Authors

  • Marcel Franz

    • University of British Columbia

  • Pavel Volkov

    • Harvard University; University of Connecticut
    • Rutgers University
    • Harvard University; University of Connecticut; Rutgers University

  • Etienne Lantagne-Hurtubise

    • California Institute of Technology
    • Caltech

  • Tarun Tummuru

    • University of British Columbia

  • Stephan Plugge

    • University of British Columbia

  • Jedediah H Pixley

    • Rutgers University, New Brunswick
    • Rutgers University, Flatiron Institute
    • Department of Physics and Astronomy, Center for Materials Theory, Rutgers University, Piscataway, NJ, 08854, USA
    • Rutgers University