Promotion of superconductivity in magic-angle graphene multilayers

Journal Article · 30 September 2022 · Science

DOI:https://doi.org/10.1126/science.abn8585· OSTI ID:1980745

Zhang, Yiran ^[1]; Polski, Robert ^[2]; Lewandowski, Cyprian ^[3]; Thomson, Alex ^[4]; Peng, Yang ^[5]; Choi, Youngjoon ^[1]; Kim, Hyunjin ^[1]; Watanabe, Kenji ^[6]; Taniguchi, Takashi ^[6]; Alicea, Jason ^[3]; von Oppen, Felix ^[7]; Refael, Gil ^[3]; Nadj-Perge, Stevan ^[2]

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1. T. J. Watson Laboratory of Applied Physics, California Institute of Technology, Pasadena, CA 91125, USA.; Institute for Quantum Information and Matter, Department of Physics, California Institute of Technology, Pasadena, CA 91125, USA.; Department of Physics, California Institute of Technology, Pasadena, CA 91125, USA.
2. T. J. Watson Laboratory of Applied Physics, California Institute of Technology, Pasadena, CA 91125, USA.; Institute for Quantum Information and Matter, Department of Physics, California Institute of Technology, Pasadena, CA 91125, USA.
3. Institute for Quantum Information and Matter, Department of Physics, California Institute of Technology, Pasadena, CA 91125, USA.; Department of Physics, California Institute of Technology, Pasadena, CA 91125, USA.
4. Institute for Quantum Information and Matter, Department of Physics, California Institute of Technology, Pasadena, CA 91125, USA.; Department of Physics, California Institute of Technology, Pasadena, CA 91125, USA.; Department of Physics, University of California, Davis, CA 95616, USA.
5. Department of Physics and Astronomy, California State University, Northridge, CA 91330, USA.
6. National Institute for Materials Science, Namiki 1-1, Tsukuba, Ibaraki 305 0044, Japan.
7. Dahlem Center for Complex Quantum Systems and Fachbereich Physik, Freie Universität Berlin, 14195 Berlin, Germany.

Graphene moiré superlattices show an abundance of correlated insulating, topological, and superconducting phases. Whereas the origins of strong correlations and nontrivial topology can be directly linked to flat bands, the nature of superconductivity remains enigmatic. We demonstrate that magic-angle devices made of twisted tri-, quadri-, and pentalayer graphene placed on monolayer tungsten diselenide exhibit flavor polarization and superconductivity. We also observe insulating states in the tril- and quadrilayer arising at finite electric displacement fields. As the number of layers increases, superconductivity emerges over an enhanced filling-factor range, and in the pentalayer it extends well beyond the filling of four electrons per moiré unit cell. Our results highlight the role of the interplay between flat and more dispersive bands in extending superconducting regions in graphene moiré superlattices.

• Research Organization: California Institute of Technology (CalTech), Pasadena, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• DOE Contract Number: SC0019166
• OSTI ID: 1980745
• Journal Information: Science, Vol. 377, Issue 6614; ISSN 0036-8075
• Publisher: AAAS
• Country of Publication: United States
• Language: English

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