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

Cea, Tommaso; Walet, Niels R.; Guinea, F.

doi:10.1103/physrevb.100.205113

Cited by 119 publications

(130 citation statements)

References 69 publications

(131 reference statements)

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“…Figure 5 shows that the extra electron fill the flat states and align the Dirac point with the Fermi energy. Small modifications in the electronic band structure as a result of new electrostatic contributions is observed, similarly to other twisted multilayer systems [68][69][70][71].…”

Section: Impact Of Chemical Dopingmentioning

confidence: 60%

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: Impact Of Chemical Dopingmentioning

confidence: 60%

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

López-Bezanilla

Lado

2020

Phys. Rev. Research

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“…van Hove energy. Most important corrections to the van Hove energy ( v ) comes from various interaction effects [67][68][69]. This may not only alter the value of v but also displace the vHS in the k space.…”

Section: Discussionmentioning

confidence: 99%

Transport across twist angle domains in moiré graphene

Padhi

Tiwari

Neupert

et al. 2020

Phys. Rev. Research

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Many experiments in twisted bilayer graphene (TBG) differ from each other in terms of the details of their phase diagrams. Few controllable aspects aside, this discrepancy is largely believed to arise from the presence of a varying degree of twist angle inhomogeneity across different samples. Real-space maps indeed reveal TBG devices splitting into several large domains of different twist angles. Motivated by these observations, we study the quantum mechanical tunneling across a domain wall (DW) that separates two such regions. We show that the tunneling of the moiré particles can be understood by the formation of an effective step potential at the DW. The height of this step potential is simply a measure of the difference in twist angles. These computations lead us to identify the global transport signatures for detecting and quantifying the local twist angle variations. In particular, using Landauer-Büttiker formalism, we compute single-channel conductance (dI/dV) and Fano factor for shot noise (ratio of noise power and mean current). A reduction in the low-energy conductance and a zero-bias sub-meV gap in the conductance are observed which scale with the twist angle difference. One of the key findings of our work is that transport in presence of twist angle inhomogeneity is "noisy," though sub-Poissonian. In particular, the differential Fano factor peaks near the van Hove energies corresponding to the domains in the sample. The location and the strength of the peak are simply a measure of the degree of twist angle inhomogeneity.

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“…It is well known, however, that long-ranged interactions play an important role in tBLG. Using Hartree theory, several groups [46][47][48][49][50] demonstrated that long-ranged interactions result in significant changes of the electronic structure which depend sensitively on doping and twist angle. In particular, Hartree interactions result in a flattening of the doped bands (in addition to the band flattening induced by twisting) [26][27][28][29].…”

Section: Introductionmentioning

confidence: 99%

Importance of long-ranged electron-electron interactions for the magnetic phase diagram of twisted bilayer graphene

et al. 2021

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Electron-electron interactions are intrinsically long ranged, but many models of strongly interacting electrons only take short-ranged interactions into account. Here, we present results of atomistic calculations including both long-ranged and short-ranged electron-electron interactions for the magnetic phase diagram of twisted bilayer graphene and demonstrate that qualitatively different results are obtained when long-ranged interactions are neglected. In particular, we use Hartree theory augmented with Hubbard interactions and calculate the interacting spin susceptibility at a range of doping levels and twist angles near the first magic angle to identify the dominant magnetic instabilities. At the magic angle, mostly antiferromagnetic order is found, while ferromagnetism dominates at other twist angles. Moreover, long-ranged interactions significantly increase the twist angle window in which strong correlation phenomena can be expected. These findings are in good agreement with available experimental data.

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

Cited by 119 publications

References 69 publications

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

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

Transport across twist angle domains in moiré graphene

Importance of long-ranged electron-electron interactions for the magnetic phase diagram of twisted bilayer graphene

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