Enhanced intervalley scattering of twisted bilayer graphene by periodic<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>A</mml:mi><mml:mi>B</mml:mi></mml:mrow></mml:math>stacked atoms

Meng, Lan; Chu, Zhaodong; Zhang, Yanfeng; Yang, Juntao; Dou, Rui-Fen; Nie, Jia-Cai; He, Lin

doi:10.1103/physrevb.85.235453

Cited by 31 publications

(33 citation statements)

References 39 publications

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“…To further understand our experimental result, we calculated the effects of both the strain and curvature on the electronic band structures of the twisted graphene bilayer by tight-binding model with the Hamiltonian 20,42,57 . In the flat region around the wrinkle, the lattices of the twisted graphene bilayer are compressed several percentages in a prescribed direction and the out-of-plane distortion of the sample is very small.…”

Section: Discussionmentioning

confidence: 99%

Strain and curvature induced evolution of electronic band structures in twisted graphene bilayer

et al. 2013

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It is well established that strain and geometry could affect the band structure of graphene monolayer dramatically. Here we study the evolution of local electronic properties of a twisted graphene bilayer induced by a strain and a high curvature, which are found to strongly affect the local band structures of the twisted graphene bilayer. The energy difference of the two low-energy van Hove singularities decreases with increasing lattice deformation and the states condensed into well-defined pseudo-Landau levels, which mimic the quantization of massive chiral fermions in a magnetic field of about 100 T, along a graphene wrinkle. The joint effect of strain and out-of-plane distortion in the graphene wrinkle also results in a valley polarization with a significant gap. These results suggest that strained graphene bilayer could be an ideal platform to realize the high-temperature zero-field quantum valley Hall effect.

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Section: Discussionmentioning

confidence: 99%

Strain and curvature induced evolution of electronic band structures in twisted graphene bilayer

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“…9 Graphene layers with a twist can now be grown by a variety of methods, which allow one to access a range of twist angles. [10][11][12] However, the nature and extent of the interlayer coupling, and the consequences thereof, continue to be debated. 13 The question then arises: in what way are these properties altered upon the introduction of defects in TBLG?…”

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confidence: 99%

Point defects in twisted bilayer graphene: A density functional theory study

Ulman

Narasimhan

2014

Phys. Rev. B

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We have used ab initio density functional theory, incorporating van der Waals corrections, to study twisted bilayer graphene (TBLG) where Stone-Wales defects or monovacancies are introduced in one of the layers. We compare these results to those for defects in single layer graphene or Bernal stacked graphene. The energetics of defect formation is not very sensitive to the stacking of the layers or the specific site at which the defect is created, suggesting a weak interlayer coupling. However signatures of the interlayer coupling are manifested clearly in the electronic band structure. For the "γγ" Stone Wales defect in TBLG, we observe two Dirac cones that are shifted in both momentum space and energy. This up/down shift in energy results from the combined effect of a charge transfer between the two graphene layers, and a chemical interaction between the layers, which mimics the effects of a transverse electric field. Charge density plots show that states near the Dirac points have significant admixture between the two layers. For Stone Wales defects at other sites in TBLG, this basic structure is modified by the creation of mini gaps at energy crossings. For a monovacancy, the Dirac cone of the pristine layer is shifted up in energy by ∼ 0.25 eV due to a combination of the requirements of the equilibration of Fermi energy between the two layers with different numbers of electrons, charge transfer, and chemical interactions. Both kinds of defects increase the density of states at the Fermi level. The monovacancy also results in spin polarization, with magnetic moments on the defect of 1.2 -1.8 µB.PACS numbers: 73.22. Pr, 71.15.Mb

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“…The linear DOS around the Dirac point E D consists well with that of the pristine graphene. The position of the Dirac point E D is slightly above the Fermi level, suggesting charge transfer between the graphene and the substrate [39][40][41].…”

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Superlattice Dirac points and space-dependent Fermi velocity in a corrugated graphene monolayer

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Recent studies show that periodic potentials can generate superlattice Dirac points at energies ±ћν F |G|/2 in graphene (ν F is the Fermi velocity of graphene and G is the reciprocal superlattice vector). Here, we perform scanning tunneling microscopy and spectroscopy studies of a corrugated graphene monolayer on Rh foil. We show that the quasi-periodic ripples of nanometer wavelength in the corrugated graphene give rise to weak one-dimensional (1D) electronic potentials and thereby lead to the emergence of the superlattice Dirac points. The position of the superlattice Dirac point is space-dependent and shows a wide distribution of values. We demonstrated that the space-dependent superlattice Dirac points is closely related to the space-dependent Fermi velocity, which may arise from the effect of the local strain and the strong electron-electron interaction in the corrugated graphene.Since the laboratory realization of graphene in 2004 [1], this two-dimensional honeycomb lattice of carbon atoms has motivated intense theoretical and experimental investigations of its properties [2][3][4][5][6][7][8]. It was demonstrated that the electronic chirality (the spinorlike structure of the wavefunction) is of central importance to many of graphene's unique electronic properties [3,[9][10][11][12]. Recently, a number of theoretical studies predicted that the chiral nature of charge carriers results in highly anisotropic behaviours of massless Dirac fermions in graphene under periodic potentials and generates new Dirac points at energies E SD = ±ћν F |G|/2 in graphene superlattice (here ν F is the Fermi velocity of graphene and G is the reciprocal superlattice vector) [13][14][15][16]. Despite these suggestive findings [13][14][15][16] and many other interesting physics [17][18][19][20][21][22] in graphene superlattice, the experimental study of this system is scarce due to the difficulty in fabricating graphene under nano-scale periodic potentials [23]. Until recently, it was demonstrated that graphene superlattice (corrugated graphene or moiré pattern) induced between the top graphene layer and the substrate (or the underlayer graphene) acts as a weak periodic potential, which generates superlattice Dirac points at an energy determined by the period of the potential [24][25][26]. These seminal experiments provide a facile method to realize graphene superlattice and open opportunities for superlattice engineering of electronic properties in graphene.In this Letter, we address the electronic structures of a corrugated graphene monolayer on Rh foil. We show that the quasi-periodic ripples of nanometer wavelength give rise to a weak one-dimensional (1D) electronic potential in graphene. This 1D potential leads to the emergence of the superlattice Dirac points E SD , which are manifested by two dips in the density of states, symmetrically placed at energies flanking the pristine graphene Dirac point E D . The position of E SD is space-dependent and shows a wide distribution of values. Our experimental result demonstrates tha...

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Enhanced intervalley scattering of twisted bilayer graphene by periodicABstacked atoms

Cited by 31 publications

References 39 publications

Strain and curvature induced evolution of electronic band structures in twisted graphene bilayer

Strain and curvature induced evolution of electronic band structures in twisted graphene bilayer

Point defects in twisted bilayer graphene: A density functional theory study

Superlattice Dirac points and space-dependent Fermi velocity in a corrugated graphene monolayer

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