Temperature dependent measurements on two decoupled graphene monolayers

Schmidt, Hennrik; Lüdtke, T.; Barthold, P.; Haug, Rolf J.

doi:10.1016/j.physe.2009.11.144

Cited by 7 publications

(11 citation statements)

References 15 publications

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“…Given that the inter-layer distances are only somewhat larger than the spatial extent of the graphene p z orbitals [25], it seems likely that both the finite thickness of the graphene layer, and its polarizability [26], could increase the inter-layer capacitance. Another possible effect is Fermi velocity reduction, which has been demon- strated to occur in twisted bilayers at small twist angles [6,11,12,27]. In this case, since we assume v F to be the same as in isolated MLG, the inter-layer capacitance could be even larger than we estimate and our extracted capacitance C GG sets a lower-bound on this quantity.…”

mentioning

confidence: 81%

Quantum Hall Effect, Screening, and Layer-Polarized Insulating States in Twisted Bilayer Graphene

et al. 2012

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We investigate electronic transport in dual-gated twisted bilayer graphene. Despite the subnanometer proximity between the layers, we identify independent contributions to the magnetoresistance from the graphene Landau level spectrum of each layer. We demonstrate that the filling factor of each layer can be independently controlled via the dual gates, which we use to induce Landau level crossings between the layers. By analyzing the gate dependence of the Landau level crossings, we characterize the finite inter-layer screening and extract the capacitance between the atomically-spaced layers. At zero filling factor, we observe magnetic and displacement field dependent insulating states, which indicate the presence of counter-propagating edge states with inter-layer coupling.

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confidence: 81%

Quantum Hall Effect, Screening, and Layer-Polarized Insulating States in Twisted Bilayer Graphene

et al. 2012

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“…As the merging point between the two layers' dispersions is lowered by an amount of

t^{θ}

, the Fermi velocity

v_{F}

in the bands below gets renormalized. Significantly reduced values (down to ∼50% of the original

v_{F} \approx 1 \times 10^{6} m s^{- 1}

) have been extracted from temperature‐dependent damping of SdH oscillations in magnetoresistance and from the energetic spacing of Landau levels in STS measurements, in most cases observing electron‐hole asymmetry with stronger reduction in the hole‐branch of the dispersion. (Notice that thusly extracted values can only represent the average of a potentially warped and anisotropic TBG dispersion.)…”

Section: Electronic Properties and Magnetotransportmentioning

confidence: 99%

Twisted Bilayer Graphene: Interlayer Configuration and Magnetotransport Signatures

Rode¹,

Смирнов²,

Belke³

et al. 2017

Annalen der Physik

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Twisted Bilayer Graphene may be viewed as very first representative of the now booming class of artificially layered 2D materials. Consisting of two sheets from the same structure and atomic composition, its decisive degree of freedom lies in the rotation between crystallographic axes in the individual graphene monolayers. Geometrical consideration finds angle-dependent Moiré patterns as well as commensurate superlattices of opposite sublattice exchange symmetry. Beyond the approach of rigidly interposed lattices, this review takes focus on the evolving topic of lattice corrugation and distortion in response to spatially varying lattice registry. The experimental approach to twisted bilayers requires a basic control over preparation techniques; important methods are summarized and extended on in the case of bilayers folded from monolayer graphene via AFM nanomachining. Central morphological parameters to the twisted bilayer, rotational mismatch and interlayer separation are studied in a broader base of samples. Finally, experimental evidence for a number of theoretically predicted, controversial electronic scenarios are reviewed; magnetotransport signatures are discussed in terms of Fermi velocity, van Hove singularities and Berry phase and assessed with respect to the underlying experimental conditions, thereby referring back to the initially considered variations in relaxed lattice structure.

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“…While the so far mentioned results can be explained by the model of two independent monolayers conducting in parallel with additional screening effects, there are some differences which are observed at temperature dependent measurements. From the temperature dependent damping of the SdH oscillations, cyclotron masses are deducted [9], showing values higher as expected for a single monolayer devices. This is directly connected to a reduced Fermi velocity in such twisted samples, as predicted by theory [10].…”

Section: B V Bg Si Sio2mentioning

confidence: 59%

Transport Measurements on Twisted Graphene Monolayers

Schmidt¹,

Lüdtke²,

Barthold³

et al. 2011

AIP Conference Proceedings

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Twisted graphene monolayers form a sample of two closely spaced two dimensional systems. We have performed transport measurements on such decoupled graphene layers being jointly contacted and conducting in parallel to investigate the properties of charge carriers in both layers. Varying the charge carrier concentration and applying perpendicular magnetic field, the electric field effect, Shubnikov-de Haas oscillations and plateaus in the Hall resistance are observed. At the charge neutrality point, the resistance decreases by 15 percent with increasing temperature from 1.5 to 50 Kelvin.

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Temperature dependent measurements on two decoupled graphene monolayers

Cited by 7 publications

References 15 publications

Quantum Hall Effect, Screening, and Layer-Polarized Insulating States in Twisted Bilayer Graphene

Quantum Hall Effect, Screening, and Layer-Polarized Insulating States in Twisted Bilayer Graphene

Twisted Bilayer Graphene: Interlayer Configuration and Magnetotransport Signatures

Transport Measurements on Twisted Graphene Monolayers

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