Phonons in few-layer graphene and interplanar interaction: A first-principles study

“…Generally, the phonon spectrum of bilayer graphene, which has been calculated using density functional theory [282,283] and force-constant models [284,285], is similar to that of monolayer. Near the Γ point there are additional low-frequency modes.…”

Section: B Phonons In Bilayer Graphenementioning

confidence: 99%

The electronic properties of bilayer graphene

2013

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We review the electronic properties of bilayer graphene, beginning with a description of the tightbinding model of bilayer graphene and the derivation of the effective Hamiltonian describing massive chiral quasiparticles in two parabolic bands at low energy. We take into account five tight-binding parameters of the Slonczewski-Weiss-McClure model of bulk graphite plus intra-and interlayer asymmetry between atomic sites which induce band gaps in the low-energy spectrum. The Hartree model of screening and band-gap opening due to interlayer asymmetry in the presence of external gates is presented. The tight-binding model is used to describe optical and transport properties including the integer quantum Hall effect, and we also discuss orbital magnetism, phonons and the influence of strain on electronic properties. We conclude with an overview of electronic interaction effects. CONTENTS

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“…63. It should be noted however, that in the literature a range of values (±30%) can be found for this constant 49,64,65 . Furthermore a small dependence of Ω ν on layer rotation is suggested 49 , which is neglected in this work as it does not affect our results noticeably.…”

Section: Computational Detailsmentioning

confidence: 97%

Electron-phonon scattering and in-plane electric conductivity in twisted bilayer graphene

et al. 2016

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We have surveyed the in-plane transport properties of the graphene twist bilayer using (i) a lowenergy effective Hamiltonian for the underlying electronic structure, (ii) an isotropic elastic phonon model, and (iii) the linear Boltzmann equation for elastic electron-phonon scattering. We find that transport in the twist bilayer is profoundly sensitive to the rotation angle of the constituent layers. Similar to the electronic structure of the twist bilayer the transport is qualitatively different in three distinct angle regimes. At large angles (θ > ≈10• ) and at temperatures below an interlayer BlochGrüneisen temperature of ≈ 10 K the conductivity is independent of the twist angle i.e. the layers are fully decoupled. Above this temperature the layers, even though decoupled in the ground state, are re-coupled by electron-phonon scattering and the transport is different both from single layer graphene as well as the Bernal bilayer. In the small angle regime θ < ≈2• the conductivity drops by two orders of magnitude and develops a rich energy dependence, reflecting the complexity of the underlying topological changes (Lifshitz transitions) of the Fermi surface. At intermediate angles the conductivity decreases continuously as the twist angle is reduced, while the energy dependence of the conductivity presents two sharp transitions, that occur at specific angle dependent energies, and that may be related to (i) the well studied van Hove singularity of the twist bilayer and (ii) a Lifshitz transition that occurs when trigonally placed electron pockets decorate the strongly warped Dirac cone. Interestingly, we find that, while the electron-phonon scattering is dominated by layer symmetric flexural phonons in the small angle limit, at large angles, in contrast, it is the layer anti-symmetric flexural mode that is most important. We examine the role of a layer perpendicular electric field finding that it affects the conductivity strongly at low temperatures whereas this effect is washed out by Fermi smearing at room temperatures.

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Phonons in few-layer graphene and interplanar interaction: A first-principles study

Cited by 72 publications

References 31 publications

Raman Spectroscopy of Graphene

Raman Spectroscopy of Graphene

The electronic properties of bilayer graphene

Electron-phonon scattering and in-plane electric conductivity in twisted bilayer graphene

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