Origin of van Hove singularities in twisted bilayer graphene

Ribeiro, Henrique B.; Sato, Kentaro; Eliel, Gomes S. N.; Souza, E. A. Thoroh de; Lu, Chun Chieh; Chiu, Po‐Wen; Saito, Riichiro; Pimenta, M. A.

doi:10.1016/j.carbon.2015.04.005

Cited by 37 publications

(50 citation statements)

References 29 publications

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“…Finally, the calculated I norm versus θ corresponds very well to the available experimental Raman data for a number of tBLG and five laser excitations (Fig. (d)).…”

Section: Resultssupporting

confidence: 76%

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Raman bands of twisted bilayer graphene

Popov

2017

J Raman Spectroscopy

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A theoretical approach to the modelling of the resonant Raman scattering by phonons in twisted bilayer graphene is developed and presented. The normally very large unit cells of twisted bilayer graphene hinder the large scale calculation of the electronic, vibrational, and optical properties by microscopic models. Here, a perturbative approach within a non-orthogonal tight-binding model is proposed that allows for a significant reduction of the computational time for such calculations. This approach is applied to the electronic band structure, electronic density of states, dielectric function, and Raman excitation profile of the most intense first-order Raman band -the G band -for twisted bilayer graphene with up to a few hundred carbon atoms in the unit cell. The computational scheme can easily be extended to second-order Raman bands of twisted bilayer graphene as well. The obtained theoretical predictions can be used for characterization of twisted bilayer graphene samples, using experimental Raman data.

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“…Finally, the calculated I norm versus θ corresponds very well to the available experimental Raman data for a number of tBLG and five laser excitations (Fig. (d)).…”

Section: Resultssupporting

confidence: 76%

“…The solid circles are values at the crossings of the REPs and the dotted lines in panel (b). The experimental data are drawn with empty triangles, empty squares, and empty circles …”

Section: Resultsmentioning

confidence: 99%

Raman bands of twisted bilayer graphene

Popov

2017

J Raman Spectroscopy

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“…The rotation of one layer relative to another can bring about new Raman features associated with phonons that are folded to the center of the Moiré pattern Brillouin zone. Twisted bilayer graphene, for example, proved to be a very interesting system, where properties can be dependent on the twisting angle, and its electronic structure has been intensively probed by Raman spectroscopy . Twisted bilayer MoS 2 has also been investigated providing valuable information about the coupling between the two layers .…”

Section: Conclusion and New Perspectivesmentioning

confidence: 99%

Raman spectroscopy in black phosphorus

Ribeiro

Pimenta

Matos

2017

J Raman Spectroscopy

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110

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In this article, we review the current status of Raman spectroscopy in orthorhombic black phosphorus (BP) (for simplicity, henceforth, referred to as BP). BP is a layered semiconductor crystal that recently regained interest because it can be exfoliated down to the single layer, thus exhibiting 2-D properties. First, we briefly review the crystalline structure and the phonon dispersion relations in BP. Then, the symmetries of the Raman-active modes are discussed in the light of group theory, and the scattering configurations for observing the different phonon modes are presented. Polarized Raman spectroscopy results are discussed and reveal unusual angular dependence features, which can be ascribed to the linear dichroism and to the complex nature of the electron-phonon matrix elements. Edge phonon effects originated from rearrangements of the atomic terminations are also discussed. Subsequently, Raman modes that emerge from interlayer interaction and that are only visible in the few-layer regime are presented and discussed. Finally, we outline new perspectives to BP Raman spectroscopy in directions that remain partially or totally unexplored and that can provide potentially important outcomes to problems such as defects, oxidation, doping, strain, stacking order and other BP-like 2-D materials.

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“…In the calculation, we use primitive vectors T 1 =na 1 +ma 2 and T 2 =(n+m)a 1 -na 2 for (n,m) tBLG [14]. Here a 1 =a(√3/2,1/2), a 2 =a(√3/2,-1/2), a=|a 1 |=|a 2 | are the primitive vectors and lattice constants for monolayer graphene, respectively.…”

Section: Calculationsmentioning

confidence: 99%

Fine tuning of optical transition energy of twisted bilayer graphene via interlayer distance modulation

et al. 2017

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Twisted bilayer graphene (tBLG) represents a family of unique materials with optoelectronic properties tuned by the rotation angle between the two layers. The presented work shows an additional way of tweaking the electronic structure of tBLG: by modifying the interlayer 2 distance, for example by a small uniaxial out-of-plane compression. We have focused on the optical transition energy, which shows a clear dependence on the interlayer distance, both experimentally and theoretically.

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Origin of van Hove singularities in twisted bilayer graphene

Cited by 37 publications

References 29 publications

Raman bands of twisted bilayer graphene

Raman bands of twisted bilayer graphene

Raman spectroscopy in black phosphorus

Fine tuning of optical transition energy of twisted bilayer graphene via interlayer distance modulation

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