Built-in Bernal gap in large-angle-twisted monolayer-bilayer graphene
Abstract Atomically thin materials offer multiple opportunities for layer-by-layer control of their electronic properties. While monolayer graphene (MLG) is a zero-gap system, Bernal-stacked bilayer graphene (BLG) acquires a finite band gap when the symmetry between the layers’ potential energy is broken, usually, via a displacement electric field applied in double-gate devices. Here, we introduce a twistronic stack comprising both MLG and BLG, synthesized via chemical vapor deposition, showing a Bernal gap in the absence of external fields. Although a large (~30°) twist angle decouples the MLG and BLG electronic bands near Fermi level, proximity-induced energy shifts in the outermost layers result in a built-in asymmetry, which requires a displacement field of 0.14 V/nm to be compensated. The latter corresponds to a ~10 meV intrinsic BLG gap, a value confirmed by our thermal-activation measurements. The present results highlight the role of structural asymmetry and encapsulating environment, expanding the engineering toolbox for monolithically-grown graphene multilayers.
Authors
- Stiven Forti (ORCID: https://orcid.org/0000-0002-8939-3175)
- Vladimir I. Fal’ko (ORCID: https://orcid.org/0000-0003-0828-0310)
- Sergey Slizovskiy (ORCID: https://orcid.org/0000-0003-0131-0775)
- Sergio Pezzini (ORCID: https://orcid.org/0000-0003-4289-907X)
- Fabio Beltram (ORCID: https://orcid.org/0000-0002-6081-436X)
- Camilla Coletti (ORCID: https://orcid.org/0000-0002-8134-7633)
- Takashi Taniguchi (ORCID: https://orcid.org/0000-0002-1467-3105)
- Kenji Watanabe (ORCID: https://orcid.org/0000-0003-3701-8119)
- Antonio Rossi (ORCID: https://orcid.org/0000-0003-4574-7215)
- Vaidotas Mišeikis (ORCID: https://orcid.org/0000-0001-6263-4250)
- Zewdu M. Gebeyehu (ORCID: https://orcid.org/0000-0001-6451-6100)
- Alex Boschi (ORCID: https://orcid.org/0000-0001-7562-7340)
Institutions
- Scuola Normale Superiore (IT)
- National Institute for Materials Science (JP)
- University of Manchester (GB)
- Italian Institute of Technology (IT)
- Henry Royce Institute (GB)
- Istituto Nanoscienze (IT)
- Center for Nanotechnology Innovation (IT)
Publication Details
- Journal
- Communications Physics
- Published
- 2024-12-01
- DOI
- https://doi.org/10.1038/s42005-024-01887-0
- Citations
- 6
- Primary Topic
- Graphene research and applications
- Type
- article
- Field-Weighted Citation Impact
- 0.70
Funders
- Graphene Flagship
- European Commission
- Ministry of Education, Culture, Sports, Science and Technology
- Ministero dell’Istruzione, dell’Università e della Ricerca
- Engineering and Physical Sciences Research Council
- Japan Society for the Promotion of Science
- Core Research for Evolutional Science and Technology