Superconductivity from Spin-Canting Fluctuations in Rhombohedral Graphene
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1.
California Institute of Technology
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2.
Université de Sherbrooke
Abstract
Rhombohedral graphene multilayers host various broken-symmetry metallic phases as well as superconductors whose pairing mechanism and order parameter symmetry remain unsettled. Strikingly, experiments have revealed prominent superconducting regions in rhombohedral bilayer and trilayer graphene devices with proximity-induced Ising spin-orbit coupling. We propose that these superconductors descend from a common spin-canted normal state that spontaneously breaks a U(1) spin symmetry and thus supports soft magnon modes. In particular, we show that these soft modes can mediate pairing through interband scattering events that are symmetry forbidden in the absence of spin-orbit coupling, thus providing a promising explanation for spin-orbit-enabled pairing. Numerous other experimental observations—including nontrivial dependence of superconductivity on the spin-orbit coupling strength, in-plane magnetic fields, and Fermi surface structure—also naturally follow from our scenario.
Copyright and License
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.
Acknowledgement
We are grateful to Trevor Arp, Erez Berg, Nick Bultinck, Andrey Chubukov, Julian Ingham, Long Ju, Hyunjin Kim, Patrick Lee, Leonid Levitov, Cyprian Lewandowski, Stevan Nadj-Perge, Caitlin Patterson, Gal Shavit, Owen Sheekey, Tomohiro Soejima, Alex Thomson, Yaar Vituri, Andrea Young, and Yiran Zhang for insightful discussions. We want to thank Alex Thomson and Johnson Guanyao Chen for pointing out a mistake in the previous version of this manuscript, where we obtained an intraband two-magnon pairing interaction involving intermediate electrons away from the Fermi surfaces that diverged as 𝑞 →0. This divergence is, in fact, canceled by higher-order terms in the magnon-fermion coupling [59].
Funding
Z. D. and É. L.-H. were supported by the Gordon and Betty Moore Foundation’s EPiQS Initiative, Grant No. GBMF8682. Portions of this work were supported by the U.S. Department of Energy, Office of Science, National Quantum Information Science Research Centers, Quantum Science Center (derivation of magnon spectrum and magnon-mediated interactions, J. A.). Additional support was provided by the Caltech Institute for Quantum Information and Matter, a National Science Foundation (NSF) Physics Frontiers Center (NSF Grant No. PHY-2317110).
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Additional details
Related works
- Is new version of
- Discussion Paper: arXiv:2406.17036 (arXiv)
Funding
- Gordon and Betty Moore Foundation
- GBMF8682
- United States Department of Energy
- National Quantum Information Science Research Centers
- Quantum Science Center
- Caltech Institute for Quantum Information and Matter
- National Science Foundation
- PHY-2317110
Dates
- Submitted
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2024-07-22
- Accepted
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2026-02-12
Caltech Custom Metadata
- Caltech groups
- Physics Department , Walter Burke Institute for Theoretical Physics , Institute for Quantum Information and Matter , Division of Physics, Mathematics and Astronomy (PMA)
- Publication Status
- Published