Direct View of Gate-Tunable Miniband Dispersion in Graphene Superlattices Near the Magic Twist Angle
Superlattices from twisted graphene mono- and bilayer systems give rise to on-demand many-body states such as Mott insulators and unconventional superconductors. These phenomena are ascribed to a combination of flat bands and strong Coulomb interactions. However, a comprehensive understanding is lacking because the low-energy band structure strongly changes when an electric field is applied to vary the electron filling. Here, we gain direct access to the filling-dependent low-energy bands of twisted bilayer graphene (TBG) and twisted double bilayer graphene (TDBG) by applying microfocused angle-resolved photoemission spectroscopy to in situ gated devices. Our findings for the two systems are in stark contrast: the doping-dependent dispersion for TBG can be described in a simple model, combining a filling-dependent rigid band shift with a many-body-related bandwidth change. In TDBG, on the other hand, we find a complex behavior of the low-energy bands, combining nonmonotonous bandwidth changes and tunable gap openings, which depend on the gate-induced displacement field. Our work establishes the extent of electric field tunability of the low-energy electronic states in twisted graphene superlattices and can serve to underpin the theoretical understanding of the resulting phenomena.
Authors
- Søren Ulstrup (ORCID: https://orcid.org/0000-0001-5922-4488)
- Jeil Jung (ORCID: https://orcid.org/0000-0003-2523-0905)
- Paulina Majchrzak (ORCID: https://orcid.org/0000-0002-5200-3866)
- Chakradhar Sahoo (ORCID: https://orcid.org/0000-0002-2043-1807)
- Kimberly Hsieh (ORCID: https://orcid.org/0000-0001-7229-9636)
- Philip Hofmann (ORCID: https://orcid.org/0000-0002-7367-5821)
- Takashi Taniguchi (ORCID: https://orcid.org/0000-0002-1467-3105)
- Kenji Watanabe (ORCID: https://orcid.org/0000-0003-3701-8119)
- Yong P. Chen (ORCID: https://orcid.org/0000-0002-7356-4179)
- Youngju Park (ORCID: https://orcid.org/0000-0001-7671-6142)
- Jill A. Miwa (ORCID: https://orcid.org/0000-0001-8392-2630)
- Alfred J. H. Jones (ORCID: https://orcid.org/0000-0002-7930-0967)
- Dongkyu Lee (ORCID: https://orcid.org/0000-0001-8658-1587)
- Zhihao Jiang (ORCID: https://orcid.org/0000-0002-4203-1062)
- Thomas S. Nielsen
Institutions
- University of Seoul (KR)
- Aarhus University (DK)
- National Institute for Materials Science (JP)
- Purdue University West Lafayette (US)
Publication Details
- Journal
- ACS Nano
- Published
- 2025-01-09
- DOI
- https://doi.org/10.1021/acsnano.4c12905
- Citations
- 3
- Primary Topic
- Graphene research and applications
- Type
- article
- Field-Weighted Citation Impact
- 1.55
Funders
- Aarhus Universitet
- Villum Fonden
- Ministry of Education, Culture, Sports, Science and Technology
- University of Seoul
- Aarhus Universitets Forskningsfond
- Ministry of Land, Infrastructure and Transport
- Korea Institute of Science and Technology Information
- National Research Foundation of Korea
- Novo Nordisk
- Danmarks Frie Forskningsfond
- Novo Nordisk Fonden
- Japan Society for the Promotion of Science
- HORIZON EUROPE Marie Sklodowska-Curie Actions