Controlling the energy gap of graphene by Fermi velocity engineering

Lima, Jonas R.F.

doi:10.1016/j.physleta.2014.11.005

Cited by 49 publications

(26 citation statements)

References 35 publications

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“…which is square integrable for a state with quantum number m as long as the velocity barrier grows at large distances more rapidly than v F (r → ∞) ∼ r −2m . These wavefunctions (27) and (28) display the chiral property of total suppression of the electronic probability density on one of the the two sublattices, dependent on the sign of the angular momentum m.…”

Section: Zero-energy States In Radial Velocity Barriersmentioning

confidence: 99%

Localization of massless Dirac particles via spatial modulations of the Fermi velocity

Downing

Portnoi

2017

J. Phys.: Condens. Matter

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The electrons found in Dirac materials are notorious for being difficult to manipulate due to the Klein phenomenon and absence of backscattering. Here we investigate how spatial modulations of the Fermi velocity in two-dimensional Dirac materials can give rise to localization effects, with either full (zero-dimensional) confinement or partial (one-dimensional) confinement possible depending on the geometry of the velocity modulation. We present several exactly solvable models illustrating the nature of the bound states which arise, revealing how the gradient of the Fermi velocity is crucial for determining fundamental properties of the bound states such as the zero-point energy. We discuss the implications for guiding electronic waves in few-mode waveguides formed by Fermi velocity modulation.

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Section: Zero-energy States In Radial Velocity Barriersmentioning

confidence: 99%

Localization of massless Dirac particles via spatial modulations of the Fermi velocity

Downing

Portnoi

2017

J. Phys.: Condens. Matter

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“…In the last years, various studies have revealed that the electronic and transport properties of graphene can be controlled by a Fermi velocity engineering [43,44]. For instance, it was obtained that a Fermi velocity modulation in graphene can control the energy gap [45] and also induce an indirect energy gap in monolayer [46] and bilayer [47] graphene. The Fermi velocity can also be used to create electrons guides in graphene [48,49], to control the Fano factor [50] and to tune the electrons transmittance from 0 to 1 [51], which means that it can turn on/off the transport in graphene.…”

Section: Introductionmentioning

confidence: 99%

Perfect valley filter controlled by Fermi velocity modulation in graphene

Lins

Lima

2020

Carbon

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In this work we investigate the effects of a Fermi velocity modulation in a valley filter in graphene created by a combination of a magnetic and electric barrier. With the effective Dirac equation of the system, we use the transfer matrix formalism to obtain the transmittance. We verify that the valley transport in graphene is very sensitive to a Fermi velocity modulation, which is able to choose which valley will be filtered with perfect filtering. Also, it is possible to use a Fermi velocity modulation to filter both valleys or to make the valley filter transparent. It reveals that the Fermi velocity is a powerful tool that can be used to tune a graphene valley filter, since it has a total control in its transport properties. *

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“…A position-dependent Fermi velocity can be obtained by placing metallic planes close to the graphene lattice, which will change the electron concentration in different regions [34,35]. It has been shown, for instance, that a Fermi velocity modulation can be used to control the energy gap of graphene [36], to induce an indirect energy gap in monolayer [37] and bilayer graphene [38], to engineer the electronic structure of graphene [39,40] and to create a waveguide for electrons in graphene [34,35]. Most recently, it was shown that it is possible to tune the transmitivity of electrons in graphene from 0 to 1 with the Fermi velocity, which can be used to turn on/off the electronic transport in graphene [41].…”

Section: Introductionmentioning

confidence: 99%

Tuning the Fano factor of graphene via Fermi velocity modulation

Lima

Barbosa

Bezerra

et al. 2018

Physica E: Low-dimensional Systems and Nanostructures

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In this work we investigate the influence of a Fermi velocity modulation on the Fano factor of periodic and quasi-periodic graphene superlattices. We consider the continuum model and use the transfer matrix method to solve the Dirac-like equation for graphene where the electrostatic potential, energy gap and Fermi velocity are piecewise constant functions of the position x. We found that in the presence of an energy gap, it is possible to tune the energy of the Fano factor peak and consequently the location of the Dirac point, by a modulations in the Fermi velocity. Hence, the peak of the Fano factor can be used experimentally to identify the Dirac point. We show that for higher values of the Fermi velocity the Fano factor goes below 1/3 in the Dirac point. Furthermore, we show that in periodic superlattices the location of Fano factor peaks is symmetric when the Fermi velocity $v_A$ and $v_B$ is exchanged, however by introducing quasi-periodicity the symmetry is lost. The Fano factor usually holds a universal value for a specific transport regime, which reveals that the possibility of controlling it in graphene is a notable result.Comment: 7 pages, 8 figures. Accepted for publication in Physica E: Low-dimensional Systems and Nanostructure

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Controlling the energy gap of graphene by Fermi velocity engineering

Cited by 49 publications

References 35 publications

Localization of massless Dirac particles via spatial modulations of the Fermi velocity

Localization of massless Dirac particles via spatial modulations of the Fermi velocity

Perfect valley filter controlled by Fermi velocity modulation in graphene

Tuning the Fano factor of graphene via Fermi velocity modulation

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