Modulation of Kekulé adatom ordering due to strain in graphene

Gonzalez-Arraga, Luis; Guinea, F.; San-José, Pablo

doi:10.1103/physrevb.97.165430

Cited by 13 publications

(7 citation statements)

References 46 publications

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“…Soon after, Gamayun et al 22 studied theoretically the low energy band dispersion laws of the Kek-Y distorted graphene finding a gapless spectrum with valley-momentum locking for the charge carriers. Other recent theoretical studies of the Kek-Y phase in graphene describe its effects on Klein tunneling 32 , its interplay with mechanical strain 33,34 and the formation of multiflavor Dirac Fermions in Kekulé-textured graphene bilayers 35 .…”

Section: Introductionmentioning

confidence: 99%

Resonant transport in Kekulé-distorted graphene nanoribbons

Andrade

Carrillo-Bastos

Pantaleón

et al. 2020

Journal of Applied Physics

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The formation of a superlattice in graphene can serve as a way to modify its electronic bandstructure and thus to engineer its electronic transport properties. Recent experiments have discovered a Kekulé bond ordering in graphene deposited on top of a Copper substrate, leading to the breaking of the valley degeneracy while preserving the highly desirable feature of linearity and gapless character of its band dispersion. In this paper we study the effects of a Kekulé distortion in zigzag graphene nanoribbons in both, the subband spectrum and on its electronic transport properties. We extend our study to investigate also the electronic conductance in graphene nanoribbons composed of sequentially ordered ν = ±1 Kek-Y superlattice. We find interesting resonances in the conductance response emerging in the otherwise energy gap regions, which scales with the number of Kek-Y interfaces minus one. Such features resembles the physics of resonant tunneling behavior observed in semiconductors heterostructures. Our findings provide a possible way to measure the strenght of Kekulé parameter in graphene nanoribbons.

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Section: Introductionmentioning

confidence: 99%

Resonant transport in Kekulé-distorted graphene nanoribbons

Andrade

Carrillo-Bastos

Pantaleón

et al. 2020

Journal of Applied Physics

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“…In fact, both couple asymmetrically with each valley by breaking the inversion symmetry while preserving time reversal. Nevertheless, strain offers the advantage of being tunable and it is in intimate relation with the kekulé phase, since this phase is expected to appear in the presence of uniaxial strain 10,47 . In general, uniaxial strain alters the band structure of graphene by (1) distorting the shape of the Brillouin zone, thus changing the geometrical position of the high symmetry points due to the modification of the lattice vectors 48 , and (2) moving the Dirac cones away from the high symmetry points, since it changes unevenly the three hopping energies connecting neighboring sites 49 .…”

Section: Introductionmentioning

confidence: 99%

Valley engineering by strain in Kekulé-distorted graphene

2019

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A Kekulé bond texture in graphene modifies the electronic band structure by folding the Brillouin zone and bringing the two inequivalent Dirac points to the center. This can result, in the opening of a gap (Kek-O) or the locking of the valley degree of freedom with the direction of motion (Kek-Y). We analyze the effects of uniaxial strain on the band structure of Kekulé-distorted graphene for both textures. Using a tight-binding approach, we introduce strain by considering the hopping renormalization and corresponding geometrical modifications of the Brillouin zone. We numerically evaluate the dispersion relation and present analytical expressions for the low-energy limit. Our results indicate the emergence of a Zeeman-like term due to the coupling of the pseudospin with the pseudomagnetic strain potential which separates the valleys by moving them in opposite directions away from the center of the Brillouin zone. For the Kek-O phase, this results in a competition between the Kekulé parameter that opens a gap and the magnitude of strain which closes it. While for the Kek-Y phase, in a superposition of two shifted Dirac cones. As the Dirac cones are much closer in the supperlattice reciprocal space that in pristine graphene, we propose strain as a control parameter for intervalley scattering.

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“…The consequences of both the Kekulé distortions on the electronic and transport properties of graphene have been widely explored, for instance: Wang et al investigated the enhanced valley-dependent Klein tunneling of electrons through a rectangular potential barrier in Kek-Y graphene 9 ; Beenakker et al showed that a potential with a Kekulé modulation can generate pseudo-Andreev reflections, where incoming electrons in a certain valley are reflected in the other 10 ; the nature of valley-dependent currents in Kek-O distorted superconducting heterojunction was recently explored by Wang et al 11 ; also, recent studies by Andrade et al found, and later confirmed experimentally by Eom and Koo 1 , that the uniaxial strain in Kek-Y graphene can separate the Dirac cones away from the Γ-point 12,13 . Other studies include the proposal of a device to control the valley orientation of channel electrons based on the valley precession produced by the Kek-Y texture 14 , as well as the study of the resonant electronic transport in graphene nanoribbons with periodic Kekulé distortions 15 .…”

Section: Introductionmentioning

confidence: 93%

Valley-driven Zitterbewegung in Kekulé-distorted graphene

Santacruz,

Iglesias,

Carrillo-Bastos

et al. 2021

Preprint

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Graphene deposited on top of a Copper(111) substrate may develop a Y-shaped Kekulé bond texture (Kekulé-Y), locking the momentum of its Dirac fermions with its valley degree of freedom. As a consequence, the valley degeneracy of its band structure is broken, generating an energy dispersion with two nested Dirac cones with different Fermi velocities. In this work, we investigate the dynamics of electronic wave packets in the Kekulé-Y superlattice. We show that, as a result of the valleymomentum coupling, a valley-driven oscillatory motion of the wave packets (Zitterbewegung) could appear, but with a smaller frequency than the Zitterbewegung effect found pristine graphene. This makes Kekulé-Y graphene a compelling candidate for experimental observation of Zitterbewegung phenomenon in a two-dimensional system.

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Modulation of Kekulé adatom ordering due to strain in graphene

Cited by 13 publications

References 46 publications

Resonant transport in Kekulé-distorted graphene nanoribbons

Resonant transport in Kekulé-distorted graphene nanoribbons

Valley engineering by strain in Kekulé-distorted graphene

Valley-driven Zitterbewegung in Kekulé-distorted graphene

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