Flatbands and Perfect Metal in Trilayer Moiré Graphene

Mora, Christophe; Regnault, Nicolas; Bernevig, B. Andrei

doi:10.1103/physrevlett.123.026402

Cited by 116 publications

(90 citation statements)

References 67 publications

(74 reference statements)

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“…The electronic structure of twisted graphene trilayers [36][37][38][39][40][41] shows different features in comparison with twisted graphene bilayers [10,42]. The electronic structure of small magic angle twisted bilayer graphene features four flat bands lying around the Fermi level, with band splitting at the point of the Brillouin zone of the emergent moiré superlattice [10,42].…”

Section: Electronic Structure Of Twisted Trilayer Graphenementioning

confidence: 99%

Electrical band flattening, valley flux, and superconductivity in twisted trilayer graphene

López-Bezanilla

Lado

2020

Phys. Rev. Research

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Twisted graphene multilayers have been demonstrated to yield a versatile playground to engineer controllable electronic states. Here, by combining first-principles calculations and low-energy models, we demonstrate that twisted graphene trilayers provide a tunable system where Van Hove singularities can be controlled electrically. In particular, it is shown that besides the band flattening, bulk valley currents appear, which can be quenched by local chemical dopants. We finally show that in the presence of electronic interactions, a nonuniform superfluid density emerges whose nonuniformity gives rise to spectroscopic signatures in dispersive higher-energy bands. Our results put forward twisted trilayers as a tunable van der Waals heterostructure displaying electrically controllable flat bands and bulk valley currents.

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Section: Electronic Structure Of Twisted Trilayer Graphenementioning

confidence: 99%

Electrical band flattening, valley flux, and superconductivity in twisted trilayer graphene

López-Bezanilla

Lado

2020

Phys. Rev. Research

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“…Their stability in a broad range of angles and tunability by gates make tMBG a promising candidate for realizing robust QAH effect in a sample-independent manner. We note that previous works [28][29][30] investigated electronic properties of trilayer graphene where both top and bottom layers are rotated with respect to the middle one; such a system can host both flat bands [28,30] and a perfect metal [29].…”

Section: Introductionmentioning

confidence: 97%

Topological flat bands and correlated states in twisted monolayer-bilayer graphene

Rademaker

Protopopov

Abanin

2020

Phys. Rev. Research

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Monolayer graphene placed with a twist on top of AB-stacked bilayer graphene hosts topological flat bands in a wide range of twist angles. The dispersion of these bands and gaps between them can be efficiently controlled by a perpendicular electric field, which induces topological transitions accompanied by changes of the Chern numbers. In the regime where the applied electric field induces gaps between the flat bands, we find a relatively uniform distribution of the Berry curvature. Consequently, interaction-induced valley-and/or spin-polarized states at integer filling factors are energetically favorable. In particular, we predict a quantum anomalous Hall state at filling factors ν = 1, 3 for a range of twist angles 1 • < θ < 1.4 •. Furthermore, to characterize the response of the system to magnetic field, we computed the Hofstadter butterfly and the Wannier plot, which can be used to probe the dispersion and topology of the flat bands in this material.

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“…In contrast to tight-binding models [15][16][17], which require a substantial numerical effort because of the large size of the Moiré superlattices at small twist angles (with more than 10 4 atoms per supercell), such continuum models are a much more efficient alternative. They have recently been generalized to describe the electronic spectrum of related twisted materials, such as twisted graphene tri-layer [18,19], quadruple-layer [20][21][22] and multi-layer graphitic structures [23][24][25].…”

Section: Introductionmentioning

confidence: 99%

Electronic band structure and pinning of Fermi energy to Van Hove singularities in twisted bilayer graphene: A self-consistent approach

2019

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The emergence of flat bands in twisted bilayer graphene leads to an enhancement of interaction effects, and thus to insulating and superconducting phases at low temperatures, even though the exact mechanism is still widely debated. The position and splitting of the flat bands is also very sensitive to the residual interactions. Moreover, the low energy bands of twisted graphene bilayers show a rich structure of singularities in the density of states, van Hove singularities, which can enhance further the role of interactions. We study the effect of the long-range interactions on the bandwidth and the van Hove singularities of the low energy bands of twisted graphene bilayers. Reasonable values of the long-range electrostatic interaction lead to a band dispersion with a significant dependence on the filling. The change of the shape and position of the bands with electronic filling implies that the van Hove singularities remain close to the Fermi energy for a broad range of fillings. This result can be described as an effective pinning of the Fermi energy at the singularity. arXiv:1906.10570v2 [cond-mat.str-el]

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Flatbands and Perfect Metal in Trilayer Moiré Graphene

Cited by 116 publications

References 67 publications

Electrical band flattening, valley flux, and superconductivity in twisted trilayer graphene

Electrical band flattening, valley flux, and superconductivity in twisted trilayer graphene

Topological flat bands and correlated states in twisted monolayer-bilayer graphene

Electronic band structure and pinning of Fermi energy to Van Hove singularities in twisted bilayer graphene: A self-consistent approach

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