Perfect valley filter controlled by Fermi velocity modulation in graphene

Lins, A.R.S.; Lima, Jonas R.F.

doi:10.1016/j.carbon.2020.01.031

Cited by 20 publications

(6 citation statements)

References 59 publications

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“…On implementing the valley index in low-bias transport, graphene nanoconstrictions with definite boundaries prove to work as a valley polarizer 17,18 . There are still obstacles to integrating these structures into electronic devices, such as controllably breaking the valley degeneracy and sustaining long * saber.rostamzadeh@universite-paris-saclay.fr valley polarization and electric manipulation 19,20 . This motivates the search for new engineered honeycomb lattice materials with better valleytronics functionality.…”

Section: Introductionmentioning

confidence: 99%

Charge–pseudospin coupled diffusion in semi-Dirac graphene: pseudospin assisted valley transport

Rostamzadeh

Sarisaman

2022

New J. Phys.

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Modifying the hexagonal lattices of graphene enables the repositioning and merging of the Dirac cones which proves to be a key element in the use of these materials for alternative electronic applications such as valleytronics. Here we study the nonequilibrium transport of carriers within a system containing two Dirac cones in both standard graphene and semi-Dirac graphene. In the latter, the lattice modifications cause the relativistic and parabolic dispersion bands to coexist, furnishing the Fermi surface with a rich pseudospin texture and a versatile Dirac cones separation. We construct a kinetic theory to investigate the carrier diffusion and uncover that the pseudospin index contributes to the particle current and, like the real spin, can induce a magnetoelectric effect, and argue that the pseudospin-charge coupling can be utilized to design a pseudospin filter. We explore the charge dynamics inside a quasi-one-dimensional conductor using the drift-diffusion model and detect the pseudospin accumulation at the sample boundaries. We find that, while, for graphene, the accumulation contributes to an extra voltage drop between the sample interfaces, the semi-Dirac system presents a similar accumulation that is strikingly equipped with valley polarization, signifying an essential tool for the control of valley manipulation and chirality transport using the pseudospin.

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Section: Introductionmentioning

confidence: 99%

Charge–pseudospin coupled diffusion in semi-Dirac graphene: pseudospin assisted valley transport

Rostamzadeh

Sarisaman

2022

New J. Phys.

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“…[50,51] For graphene subject to a combination of a magnetic and electric barrier, the Fermi velocity modulation on valley transport was reported theoretically. [52] In strained and gapped graphene, spin-valley spatial separation and valley-resolved surface magnetoplasmons were demonstrated theoretically. [53,54] The time-dependent lattice vibration of optical phonon modes was proposed to realize a topological valley pump in graphene.…”

Section: Introductionmentioning

confidence: 99%

Valley filtering and valley-polarized collective modes in bulk graphene monolayers

Zheng 郑,

Zhai 翟

2024

Chinese Phys. B

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The presence of two sublattices in hexagonal graphene brings two energetically degenerate extremes in the conduction and valence band, which are identified by the valley quantum number. Recently, this valley degree of freedom has been suggested to encode and process information, which develops a new carbon-based electronics named graphene valleytronics. In this topical review, we present and discuss valley-related transport properties in bulk graphene monolayers, which are due to strain-induced pseudomagnetic fields and associated vector potential, sublattice-stagger potential, and the valley-Zeeman effect. These valley-related interactions can be utilized to obtain valley filtering, valley spatial separation, valley-resolved guiding modes, and valley-polarized collective modes such as edge or surface plasmons. The present challenges and the perspectives on graphene valleytronics are also provided in this review.

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“…[ 1 ] Regulation of the Fermi velocity in graphene can be done by several methods such as changing electric field or substrate. [ 1,4 ] In this regard, several reports demonstrated how the Fermi velocity alters graphene transport features [ 11–14 ] and its device performance. [ 15,16 ] Among graphene morphologies, quantum wells (QWs), [ 17,18 ] hetrostructures, [ 19–22 ] and superlattices (SLs) [ 23–26 ] have widely been implemented in designing/fabrication emerging devices [ 27–29 ] and exploring novel phenomenon [ 30–35 ] beyond the reach of exciting materials.…”

Section: Introductionmentioning

confidence: 99%

Fermi Velocity Modulation Induced Low‐Bias Negative Differential Resistance in Graphene Double Barrier Resonant Tunneling diode

2021

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Negative differential resistance (NDR) devices are adequate candidates for the functional devices applicable to the next‐generation integrated circuit technology so‐called “Beyond CMOS.” Here, a graphene velocity‐modulation‐barrier resonant‐tunneling diode operating at room temperature is proposed. The current–voltage characteristics of the device are analyzed using the non‐equilibrium Green's function technique. It is found that the Fermi velocity barrier in the well/barrier region manipulates the tunneling transmission probability by suppressing the Klein region and improving the resonant tunneling leading to NDR. For special values of velocity barriers, resonant states have maximum alignment with each other which increases peak current with a high peak to valley ratio (PVR). The width and the position of the NDR window are controlled and engineered by the device dimensions and the height of potential barriers. The smaller the device showed the better the NDR properties such as larger current density and maximum PVR. Taken together, the results reveal that adequate magnitude of the Fermi velocity in graphene barrier can be an impressive concept for the fabrication of emerging tunneling devices.

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Perfect valley filter controlled by Fermi velocity modulation in graphene

Cited by 20 publications

References 59 publications

Charge–pseudospin coupled diffusion in semi-Dirac graphene: pseudospin assisted valley transport

Charge–pseudospin coupled diffusion in semi-Dirac graphene: pseudospin assisted valley transport

Valley filtering and valley-polarized collective modes in bulk graphene monolayers

Fermi Velocity Modulation Induced Low‐Bias Negative Differential Resistance in Graphene Double Barrier Resonant Tunneling diode

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