Article Direct View of Gate-Tunable Miniband Dispersion in Graphene Superlattices Near the Magic Twist Angle

Zhihao Jiang ORCID ; Dongkyu Lee ; Alfred J. H. Jones ORCID ; Youngju Park ; Kimberly Hsieh ; Paulina Majchrzak ; Chakradhar Sahoo ; Thomas S. Nielsen ; Kenji Watanabe SAMURAI ORCID (National Institute for Materials ScienceROR) ; Takashi Taniguchi SAMURAI ORCID (National Institute for Materials ScienceROR) ; Philip Hofmann ; Jill A. Miwa ; Yong P. Chen ; Jeil Jung ORCID ; Søren Ulstrup ORCID

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Citation
Zhihao Jiang, Dongkyu Lee, Alfred J. H. Jones, Youngju Park, Kimberly Hsieh, Paulina Majchrzak, Chakradhar Sahoo, Thomas S. Nielsen, Kenji Watanabe, Takashi Taniguchi, Philip Hofmann, Jill A. Miwa, Yong P. Chen, Jeil Jung, Søren Ulstrup. Direct View of Gate-Tunable Miniband Dispersion in Graphene Superlattices Near the Magic Twist Angle. ACS Nano. 2025, 19 (2), 2379-2387. https://doi.org/10.1021/acsnano.4c12905

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(abstract)

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.

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Keyword: Twisted graphene, low-energy bands, photoemission spectroscopy

Date published: 2025-01-21

Publisher: American Chemical Society (ACS)

Journal:

  • ACS Nano (ISSN: 19360851) vol. 19 issue. 2 p. 2379-2387

Funding:

  • Det Frie Forskningsr??d DFF-9064-00057B
  • Novo Nordisk Fonden NNF22OC0079960
  • HORIZON EUROPE Marie Sklodowska-Curie Actions 101059528
  • Aarhus Universitets Forskningsfond
  • Korea Institute of Science and Technology Information KSC-2022-CRE-0514
  • Villum Fonden 25931
  • Ministry of Education, Culture, Sports, Science and Technology 21H05233
  • Ministry of Education, Culture, Sports, Science and Technology 23H02052
  • Ministry of Land, Infrastructure and Transport
  • Ministry of Education, Culture, Sports, Science and Technology
  • National Research Foundation of Korea NRF2020R1A5A1016518
  • Det Frie Forskningsr??d DFF-1026-00089B
  • Det Frie Forskningsr??d DFF-6108-00409

Manuscript type: Publisher's version (Version of record)

MDR DOI:

First published URL: https://doi.org/10.1021/acsnano.4c12905

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Updated at: 2025-02-05 12:30:18 +0900

Published on MDR: 2025-02-05 12:30:18 +0900

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