Valley filter in strain engineered graphene

Fujita, Takeshi; Jalil, M. B. A.; Tan, Seng Ghee

doi:10.1063/1.3473725

Cited by 220 publications

(159 citation statements)

References 24 publications

(25 reference statements)

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“…In the literature, several valley filter applications have been proposed. [9][10][11][12][13] However, they have some limitations such as practical difficulties and low filter efficiency, as reported in Ref. 11 and Ref.…”

Section: Introductionmentioning

confidence: 99%

“…16 similar to our set-up comprises of two different region, i.e., a region of strained graphene substrate which acts as a valley separator, followed by an extractor region with a local perpendicular magnetic field. 9,17 In general, the valley polarization is not close to 100%, 17 but by matching the strain and magnetic fields, ideal valley polarization can be approached. 9 In the two-barrier structure, incident electrons are polarized in angular space at the first barrier interface, before being filtered out at the second barrier interface.…”

Section: Introductionmentioning

confidence: 99%

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Perfect valley filter in strained graphene with single barrier region

et al. 2016

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We present a single barrier system to generate pure valley-polarized current in monolayer graphene. A uniaxial strain is applied within the barrier region, which is delineated by localized magnetic field created by ferromagnetic stripes at the region's boundaries. We show that under the condition of matching magnetic field strength, strain potential, and Fermi energy, the transmitted current is composed of only one valley contribution. The desired valley current can transmit with zero reflection while the electrons from the other valley are totally reflected. Thus, the system generates pure valleypolarized current with maximum conductance. The chosen parameters of uniaxial strain and magnetic field are in the range of experimental feasibility, which suggests that the proposed scheme can be realized with current technology.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Perfect valley filter in strained graphene with single barrier region

et al. 2016

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“…We model the valleytronic devices using a Landauer's ballistic transport formalism [71] for two-dimensional (2D) nanostructures. The ballistic transport picture has been widely used in the modeling of valleyfiltering effect in nanostructures [1,[17][18][19][20][21][22][23][24][25][26][27][28][29]31,34]. In realistic device, the inevitable presence of impurities, defects, and many-body effects can quantitatively change the results, but the valley-filtering effect shall qualitatively remain robust as recently demonstrated for the case of strained graphene [30].…”

Section: Valleytronic Trio: Filter Valve and Reversible Logicmentioning

confidence: 99%

“…In general, valley filters can be classified into two types: (i) gauge-field based (GF); and (ii) electrostatic-field based (EF). GF filter [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31] utilizes an external magnetic field and/or a pseudomagnetic field induced by mechanically straining the crystal [32] to break the valley transport symmetry whereas EF filter mostly relies on energy filtering in properly designed nanostructures [1,33,34] or by forming one-dimensional (1D) topological edge state in a domain wall [35][36][37][38][39][40][41][42][43]. In terms of building compact valleytronic device, EF filter is more advantageous than GF filter as the electrical output of an EF filter is intrinsically compatible with its electric-based controlling knob for valley polarization.…”

Section: Introductionmentioning

confidence: 99%

Valleytronics in merging Dirac cones: All-electric-controlled valley filter, valve, and universal reversible logic gate

et al. 2017

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Despite much anticipation of valleytronics as a candidate to replace the aging complementary metal-oxidesemiconductor (CMOS) based information processing, its progress is severely hindered by the lack of practical ways to manipulate valley polarization all electrically in an electrostatic setting. Here, we propose a class of all-electric-controlled valley filter, valve, and logic gate based on the valley-contrasting transport in a merging Dirac cones system. The central mechanism of these devices lies on the pseudospin-assisted quantum tunneling which effectively quenches the transport of one valley when its pseudospin configuration mismatches that of a gate-controlled scattering region. The valley polarization can be abruptly switched into different states and remains stable over semi-infinite gate-voltage windows. Colossal tunneling valleypseudomagnetoresistance ratio of over 10000% can be achieved in a valley-valve setup. We further propose a valleytronic-based logic gate capable of covering all 16 types of two-input Boolean logics. Remarkably, the valley degree of freedom can be harnessed to resurrect logical reversibility in two-input universal Boolean gate. The (2+1) polarization states (two distinct valleys plus a null polarization) reestablish one-to-one inputto-output mapping, a crucial requirement for logical reversibility, and significantly reduce the complexity of reversible circuits. Our results suggest that the synergy of valleytronics and digital logics may provide new paradigms for valleytronic-based information processing and reversible computing. Despite much anticipation of valleytronics as a candidate to replace the aging complementary metal-oxidesemiconductor (CMOS) based information processing, its progress is severely hindered by the lack of practical ways to manipulate valley polarization all electrically in an electrostatic setting. Here, we propose a class of all-electric-controlled valley filter, valve, and logic gate based on the valley-contrasting transport in a merging Dirac cones system. The central mechanism of these devices lies on the pseudospin-assisted quantum tunneling which effectively quenches the transport of one valley when its pseudospin configuration mismatches that of a gate-controlled scattering region. The valley polarization can be abruptly switched into different states and remains stable over semi-infinite gate-voltage windows. Colossal tunneling valley-pseudomagnetoresistance ratio of over 10 000% can be achieved in a valley-valve setup. We further propose a valleytronic-based logic gate capable of covering all 16 types of two-input Boolean logics. Remarkably, the valley degree of freedom can be harnessed to resurrect logical reversibility in two-input universal Boolean gate. The (2 + 1) polarization states (two distinct valleys plus a null polarization) reestablish one-to-one input-to-output mapping, a crucial requirement for logical reversibility, and significantly reduce the complexity of reversible circuits. Our results suggest that the synergy of va...

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“…The Hall effect that is generated by the spin Hall mechanism in graphene via the spin-orbit dynamics of the carriers can be well explored through non uniform exchange interaction [6][7][8]. As the gauge theory can be applied in describing transport in graphene [9,10], the role of momentum space and real space Berry curvature for a system with finite spin-orbit coupling is also worth studying.…”

Section: Introductionmentioning

confidence: 99%

Effect of non-uniform exchange field in ferromagnetic graphene

Chowdhury

Basu

2015

Annals of Physics

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We have presented here the consequences of the non-uniform exchange field on the spin transport issues in spin chiral configuration of ferromagnetic graphene. Taking resort to the spin orbit coupling (SOC) term and non-uniform exchange coupling term we are successful to express the expression of Hall conductivity in terms of the exchange field and SOC parameters through the Kubo formula approach. However, for a specific configuration of the exchange parameter we have evaluated the Berry curvature of the system. We also have paid attention to the study of SU(2) gauge theory of ferromagnetic graphene. The generation of anti damping spin orbit torque in spin chiral magnetic graphene is also briefly discussed.

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Valley filter in strain engineered graphene

Cited by 220 publications

References 24 publications

Perfect valley filter in strained graphene with single barrier region

Perfect valley filter in strained graphene with single barrier region

Valleytronics in merging Dirac cones: All-electric-controlled valley filter, valve, and universal reversible logic gate

Effect of non-uniform exchange field in ferromagnetic graphene

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