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Description:

Controlling the bandstructure of Dirac materials is of wide interest in current research but has remained an outstanding challenge for systems such as monolayer graphene. In contrast, Bernal bilayer graphene (BLG) offers a highly flexible platform for tuning the bandstructure. One direction is opening the bandgap by a transverse displacement field, a property which is well established and widely used. Another appealing direction is accessing the complex BLG bands consisting of mini Dirac cones with opposite chiralities occurring at low displacement field near charge neutrality, and tuning them through topological transitions and van Hove singularities. Even though BLG was extensively studied experimentally in the last two decades, the evidence of this exotic, linear bandstructure is still elusive, likely due to insufficient energy resolution. Here, rather than probing the bandstructure using spectroscopy, we use Landau levels as markers of the energy dispersion and carefully analyze the Landau level spectrum in a regime where the cyclotron orbits of electrons or holes in momentum space are small enough to resolve the distinct mini Dirac cones. We identify the presence of four distinct Dirac cones and map out complex topological transitions induced by electric displacement field. These findings introduce a valuable addition to the toolkit for graphene electronics.

Rights:

• Creative Commons BY Attribution 4.0 International
  

Keyword: ernal bilayer graphene, band structure, Landau levels

Date published: 2024-04-11

Publisher: Springer Science and Business Media LLC

Journal:

• Nature Communications (ISSN: 20411723) vol. 15 issue. 1 3133

Funding:

• Deutsche Forschungsgemeinschaft SFB 1073
• Deutsche Forschungsgemeinschaft SPP 2244
• Deutsche Forschungsgemeinschaft SFB 1073
• Deutsche Forschungsgemeinschaft SPP 2244
• MEXT | Japan Society for the Promotion of Science KAKENHI 21H05233 and 23H02052
• MEXT | Japan Society for the Promotion of Science KAKENHI 21H05233 and 23H02052

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

MDR DOI:

First published URL: https://doi.org/10.1038/s41467-024-47342-0

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Updated at: 2025-02-27 12:30:23 +0900

Published on MDR: 2025-02-27 12:30:23 +0900