Probing the tunable multi-cone band structure in Bernal bilayer graphene

Bernal bilayer graphene (BLG) offers a highly flexible platform for tuning the band structure, featuring two distinct regimes. One is a tunable band gap induced by large displacement fields. Another is a gapless metallic band occurring at low fields, featuring rich fine structure consisting of four...

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Bibliographic Details
Published in:Nature communications 2024-04, Vol.15 (1), p.3133-9, Article 3133
Main Authors: Seiler, Anna M., Jacobsen, Nils, Statz, Martin, Fernandez, Noelia, Falorsi, Francesca, Watanabe, Kenji, Taniguchi, Takashi, Dong, Zhiyu, Levitov, Leonid S., Weitz, R. Thomas
Format: Article
Language:English
Subjects:
639/766/119/2794
639/766/119/995
Band structure of solids
Bilayers
Cones
Cyclotrons
Dispersion
Energy bands
Energy gap
Energy resolution
Fine structure
Graphene
Humanities and Social Sciences
multidisciplinary
Science
Science (multidisciplinary)
Topology
Ultrastructure
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Summary:Bernal bilayer graphene (BLG) offers a highly flexible platform for tuning the band structure, featuring two distinct regimes. One is a tunable band gap induced by large displacement fields. Another is a gapless metallic band occurring at low fields, featuring rich fine structure consisting of four linearly dispersing Dirac cones and van Hove singularities. Even though BLG has been extensively studied experimentally, the evidence of this band structure is still elusive, likely due to insufficient energy resolution. Here, we use Landau levels as markers of the energy dispersion and 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 Dirac cones and map out topological transitions induced by displacement field. By clarifying the low-energy properties of BLG bands, these findings provide a valuable addition to the toolkit for graphene electronics. Bernal-stacked bilayer graphene (BLG) has been extensively studied due to its tunable band gap and emerging electronic properties, but its low-energy band structure remains debated. Here, the authors report magnetotransport measurements of Bernal BLG, showing evidence of four Dirac cones and electrically induced topological transitions.
ISSN:2041-1723
2041-1723
DOI:10.1038/s41467-024-47342-0