Towards superlattices: Lateral bipolar multibarriers in graphene

Drienovsky, Martin; Schrettenbrunner, F.-X.; Sandner, Andreas; Weiss, Dieter; Eroms, Jonathan; Liu, Ming‐Hao; Tkatschenko, Fedor; Richter, Klaus

doi:10.1103/physrevb.89.115421

Cited by 33 publications

(45 citation statements)

References 39 publications

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“…Due to its atomic-scale perfection and unique electronic structure, monolayer graphene (MLG) has emerged as an ideal 2D material to study charge transport [24]. Much attention has been paid to ballistic transport of electrons and suppression of backscattering by Klein tunneling in MLG, including the effect of p − n junctions, local and periodic gating, interaction with the substrate and presence of magnetic field [25][26][27][28][29][30][31][32][33][34][35][36][37]. The band structure of MLG at the six Fermi points in the Brillouin zone is characterized by Dirac cones, formally describing massless particles with constant v F independent of doping.…”

Section: Introductionmentioning

confidence: 99%

Periodically Gated Bilayer Graphene as an Electronic Metamaterial

Lin

Tománek

2020

Phys. Rev. Applied

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We study ballistic transport in periodically gated bilayer graphene as a candidate for a 2D electronic metamaterial. Our calculations use the equilibrium Green function formalism and take into account quantum corrections to charge density changes induced by a periodically modulated top gate voltage. Our results reveal an intriguing interference-like pattern, similar to that of a Fabry-Pérot interferometer, in the resistance map as a function of the voltage VBG applied to the extended bottom gate and VT G applied to the periodic top gate. arXiv:2001.03081v1 [cond-mat.mes-hall] 9 Jan 2020

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Section: Introductionmentioning

confidence: 99%

Periodically Gated Bilayer Graphene as an Electronic Metamaterial

Lin

Tománek

2020

Phys. Rev. Applied

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“…2a and 2b, and follow the approach proposed in Ref. [55] . We consider the tip potential as varying only along x-axis, and evaluate the position of the expected resonances from the simple equal phase condition:…”

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confidence: 99%

Optimizing Dirac fermions quasi-confinement by potential smoothness engineering

et al. 2020

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With the advent of high mobility encapsulated graphene devices, new electronic components ruled by Dirac fermions optics have been envisioned and realized. The main building blocks of electron-optics devices are gate-defined p-n junctions, which guide, transmit and refract graphene charge carriers, just like prisms and lenses in optics. The reflection and transmission are governed by the p-n junction smoothness, a parameter difficult to tune in conventional devices. Here we create p-n junctions in graphene, using the polarized tip of a scanning gate microscope, yielding Fabry-Pérot interference fringes in the device resistance. We control the p-n junctions smoothness using the tip-to-graphene distance, and show increased interference contrast using smoother potential barriers. Extensive tight-binding simulation reveal that smooth potential barriers induce a pronounced quasi-confinement of Dirac fermions below the tip, yielding enhanced interference contrast. On the opposite, sharp barriers are excellent Dirac fermions transmitters and lead to poorly contrasted interferences.Our work emphasizes the importance of junction smoothness for relativistic electron optics devices engineering.

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“…A more flexible approach to design artificial graphene superlattice structures for band structure engineering was pursued with the realization of electrostatic gating schemes [20]. To create an externally controllable periodic potential, the most intuitive way is to pattern an array of periodic fine metal gates on top of the graphene sample [42,43]. However, due to technical difficulties such as instabilities of nanometer-scale local gates, the low adhesion between metal gates and the inert hBN, etc., such superlattice graphene devices often suffer the problem of very low sample yield [44].…”

Section: B Gate-controlled Superlatticesmentioning

confidence: 99%

Electrostatic superlattices on scaled graphene lattices

et al. 2020

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A scalable tight-binding model is applied for large-scale quantum transport calculations in clean graphene subject to electrostatic superlattice potentials, including two types of graphene superlattices: moiré patterns due to the stacking of graphene and hexagonal boron nitride (hBN) lattices, and gate-controllable superlattices using a spatially modulated gate capacitance. In the case of graphene/hBN moiré superlattices, consistency between our transport simulation and experiment is satisfactory at zero and low magnetic field, but breaks down at high magnetic field due to the adopted simple model Hamiltonian that does not comprise higher-order terms of effective vector potential and Dirac mass terms. In the case of gate-controllable superlattices, no higher-order terms are involved, and the simulations are expected to be numerically exact. Revisiting a recent experiment on graphene subject to a gated square superlattice with periodicity of 35 nm, our simulations show excellent agreement, revealing the emergence of multiple extra Dirac cones at stronger superlattice modulation. arXiv:1907.03288v1 [cond-mat.mes-hall]

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Towards superlattices: Lateral bipolar multibarriers in graphene

Cited by 33 publications

References 39 publications

Periodically Gated Bilayer Graphene as an Electronic Metamaterial

Periodically Gated Bilayer Graphene as an Electronic Metamaterial

Optimizing Dirac fermions quasi-confinement by potential smoothness engineering

Electrostatic superlattices on scaled graphene lattices

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