Intervalley scattering of graphene massless Dirac fermions at 3-periodic grain boundaries

Rodrigues, J. N. B.

doi:10.1103/physrevb.94.134201

Cited by 9 publications

(8 citation statements)

References 42 publications

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“…It can be observed clearly that sizable valley currents appear in regions in the complementary regions to the low-energy states, similarly to other moiré systems [22,56]. Since the emergence of such currents relies on valley conservation, terms in the system creating intervalley mixing are expected to substantially impact them [6,[65][66][67], as we address in the next section.…”

Section: Band Flattening and Valley Currents By An Interlayer Biasmentioning

confidence: 81%

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: Band Flattening and Valley Currents By An Interlayer Biasmentioning

confidence: 81%

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

López-Bezanilla

Lado

2020

Phys. Rev. Research

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“…Compared to alternative theoretical methods [ 27 , 28 , 29 , 30 ], the present approach does not require a tight-binding model of the linear defect (grain boundary) and boundary conditions, which are expressed via the matching matrix method, are derived using the algebraic properties of the scattering problem.…”

Section: Discussionmentioning

confidence: 99%

“…Rodrigues and coworkers in Refs. [ 27 , 28 , 29 , 30 ], where specific boundary conditions have been derived from the tight-binding model of the extended defect. The mentioned approach provides a continuous model to study transport properties in the presence of selected linear defects, whose atomic arrangement determines the boundary conditions of the scattering problem.…”

Section: Introductionmentioning

confidence: 99%

Scattering Theory of Graphene Grain Boundaries

Romeo

Bartolomeo

2018

Materials

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The implementation of graphene-based electronics requires fabrication processes that are able to cover large device areas, since the exfoliation method is not compatible with industrial applications. The chemical vapor deposition of large-area graphene represents a suitable solution; however, it has an important drawback of producing polycrystalline graphene with the formation of grain boundaries, which are responsible for the limitation of the device’s performance. With these motivations, we formulate a theoretical model of a single-layer graphene grain boundary by generalizing the graphene Dirac Hamiltonian model. The model only includes the long-wavelength regime of the charge carrier transport, which provides the main contribution to the device conductance. Using symmetry-based arguments deduced from the current conservation law, we derive unconventional boundary conditions characterizing the grain boundary physics and analyze their implications on the transport properties of the system. Angle resolved quantities, such as the transmission probability, are studied within the scattering matrix approach. The conditions for the existence of preferential transmission directions are studied in relation with the grain boundary properties. The proposed theory provides a phenomenological model to study grain boundary physics within the scattering approach, and represents per se an important enrichment of the scattering theory of polycrystalline graphene. Moreover, the outcomes of the theory can contribute to understanding and limiting the detrimental effects of graphene grain boundaries, while also providing a benchmark for more elaborate techniques.

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“…[ 32,54,55 ] In the graphene sponges, 3D curved surfaces, together with grain boundaries and topological defects, could be the sources of intravalley electron scattering and/or intervalley electron scatterings. [ 27–29,36,37,56,57 ] The WL could be restored by the intervalley scattering through the mixing of K and K' valleys in the graphene electronic states. In fact, the number of possible scattering sources on the electron pathways increases when the curvature radius decreases.…”

Section: Figurementioning

confidence: 99%

Dirac Fermion Kinetics in 3D Curved Graphene

et al. 2020

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3D integration of graphene has attracted attention for realizing carbon‐based electronic devices. While the 3D integration can amplify various excellent properties of graphene, the influence of 3D curved surfaces on the fundamental physical properties of graphene has not been clarified. The electronic properties of 3D nanoporous graphene with a curvature radius down to 25–50 nm are systematically investigated and the ambipolar electronic states of Dirac fermions are essentially preserved in the 3D graphene nanoarchitectures, while the 3D curvature can effectively suppress the slope of the linear density of states of Dirac fermion near the Fermi level are demonstrated. Importantly, the 3D curvature can be utilized to tune the back‐scattering‐suppressed electrical transport of Dirac fermions and enhance both electron localization and electron–electron interaction. As a result, nanoscale curvature provides a new degree of freedom to manipulate 3D graphene electrical properties, which may pave a new way to design new 3D graphene devices with preserved 2D electronic properties and novel functionalities.

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Intervalley scattering of graphene massless Dirac fermions at 3-periodic grain boundaries

Cited by 9 publications

References 42 publications

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

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

Scattering Theory of Graphene Grain Boundaries

Dirac Fermion Kinetics in 3D Curved Graphene

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