Circular quantum dots in twisted bilayer graphene

Mirzakhani, M.; Peeters, F. M.; Zarenia, M.

doi:10.1103/physrevb.101.075413

Cited by 27 publications

(17 citation statements)

References 77 publications

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“…Finally, introducing a finite twist between the two layers is a natural extension of this work which offers further degrees of tunability, both in the spatial fluctuation of mass terms due to different stackings and the different confined or edge states in the dot regions. 102,103…”

Section: Discussionmentioning

confidence: 99%

Valley current generation using biased bilayer graphene dots

Solomon,

Power

2021

Preprint

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Intrinsic and extrinsic valley Hall effects are predicted to emerge in graphene systems with uniform or spatially-varying mass terms. Extrinsic mechanisms, mediated by the valley-dependent scattering of electrons at the Fermi surface, can be directly linked to quantum transport simulations. This is a promising route towards more complete experimental investigation of valleytronic phenomena in graphene, but a major obstacle is the difficulty in applying the sublattice-dependent potentials required. Here we show that strongly valley-dependent scattering also emerges from bilayer graphene quantum dots, where the gap size can be easily modulated using the interlayer potentials in dualgated devices. Robust valley-dependent scattering and concomitant valley currents are observed for a range of systems, and we investigate the role of dot size, mass strength and additional potential terms. Finally, we note that a strong valley splitting of electronic current also emerges when a biased bilayer dot is embedded in a single layer of graphene, but that the effect is less robust than for a bilayer host. Our findings suggest that bilayer graphene devices with custom mass profiles provide an excellent platform for future valleytronic exploration of two-dimensional materials.

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Section: Discussionmentioning

confidence: 99%

Valley current generation using biased bilayer graphene dots

Solomon,

Power

2021

Preprint

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“…along graphene nanoribbons on Au(111) [65] and along ridges on SiC(0001) [66])), but the FD special topology coupled to the interaction with the underlying graphene could induce new states due to electronic confinement. Recent calculations on circular quantum dots in twisted bilayer graphene are certainly a hint to understand those states [67].…”

Section: Mapping Of Low Energy Statesmentioning

confidence: 99%

High density synthesis of topological point defects in graphene on 6H–SiC(0001¯)

Berrahal

Amara

Bellec

et al. 2020

Carbon

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The control of the physical properties of graphene is a forefront challenge for the development of applications based on this material. Defect engineering is a promising strategy to attain new properties by the insertion of well-defined defects in the carbon lattice. Among the many topological defects of graphene, the one that has the lowest energy per dislocation is a quasi-point-like defect, the so-called Flower Defect (FD). It is generally produced randomly during the graphene synthesis. The deliberate insertion of this defect is promising for the tuning of graphene electronic properties but necessitate to establish a synthesis route allowing to control the formation of flower defects. Here we report a controlled synthesis of graphene with FD using gold as an activator during the graphene synthesis from a 6H-SiC( 0001) silicon carbide wafer. The synthesis consists of a two-step procedure. Creation of a proto-graphene template where one monolayer of gold is evaporated followed by synthesis close to 1200°C. This leads to a high density of FD, around 10 12 cm −2 . These results are supported by first-principles calculations showing that gold decreases the flower formation energy by a factor of 2. Scanning tunneling spectroscopy measurements reveal unexpected resonances close to the Fermi energy.

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“…Dot twistronics might be even more attractive from the application point of view, since we do not run into the dimension vs. quality of the prepared systems kind of problems 9 . Simple exploration of the energy scale of the created bound states (theoretically and experimentally), their behavior with changing char-acteristic length, twisting angle, as well as application of the external magnetic field create standard tools in the developing area of the dot twistronics 10,11 .…”

Section: Introductionmentioning

confidence: 99%

“…Our semianalytical approach, which allows us to examine general physical phenomena considering larger systems, is motivated by the results of the second mentioned study 11 . Its authors claim that considering the interval of large twisting angles 10 • θ 50 • , interaction between the two single sheets of graphene layers is small and the band structure basically copies the one of the two single layer sheets.…”

Section: Introductionmentioning

confidence: 99%

Large twisting angles in bilayer graphene moiré quantum dot structures

Bucko

Herman

2021

Phys. Rev. B

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Recent exploration of the commensurate structure in the turbostratic double layer graphene shows that the large angle twisting can be treated by the decrease of the effective velocity within the energy spectra of the single layer graphene. Within our work, we use this result as a starting point, aiming towards understanding the physics of by a large angle twisted double layer graphene (i.e. Moire) quantum dot systems. We show that within this simple approach using the language of the first quantization, yet another so far unrealized (not up to our knowledge), illustrative property of the commutation relation appears in the graphene physics. Intriguingly, large twisting angles show to be a suitable tunning knob of the position symmetry in the graphene systems. Complete overview of the large angle twisting on the considered dot systems is provided.

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Circular quantum dots in twisted bilayer graphene

Cited by 27 publications

References 77 publications

Valley current generation using biased bilayer graphene dots

Valley current generation using biased bilayer graphene dots

High density synthesis of topological point defects in graphene on 6H–SiC(0001¯)

Large twisting angles in bilayer graphene moiré quantum dot structures

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