Graphene bilayers with a twist

Abstract

Near a magic twist angle, bilayer graphene transforms from a weakly correlated Fermi liquid to a strongly correlated two-dimensional electron system with properties that are extraordinarily sensitive to carrier density and to controllable environmental factors such as the proximity of nearby gates and twist-angle variation. Among other phenomena, magic-angle twisted bilayer graphene hosts superconductivity, interaction-induced insulating states, magnetism, electronic nematicity, linear-in-temperature low-temperature resistivity and quantized anomalous Hall states. We highlight some key research results in this field, point to important questions that remain open and comment on the place of magic-angle twisted bilayer graphene in the strongly correlated quantum matter world.

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Fig. 1: Structure of monolayer graphene and TBG.
Fig. 2: Electronic properties of TBG.
Fig. 3: Comparison of MATBG and high-temperature superconductors.
Fig. 4: Flat-band MATBG observed with local probes.
Fig. 5: Nematicity and multiple superconducting domes in MATBG.
Fig. 6: Moiré bands and Fermi surface.
Fig. 7: Beyond MATBG.

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Acknowledgements

E.Y.A. acknowledges support from DOE (DOE-FG02-99ER45742) and the Gordon and Betty Moore Foundation (GBMF9453). A.H.M. acknowledges support from DOE BES grant DE- FG02-02ER45958 and from Welch Foundation grant TBF1473.

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Andrei, E.Y., MacDonald, A.H. Graphene bilayers with a twist. Nat. Mater. 19, 1265–1275 (2020). https://doi.org/10.1038/s41563-020-00840-0

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