Mobility Enhancement in Graphene by 
<i>in situ</i>
 Reduction of Random Strain Fluctuations

Wang, Lujun; Makk, Péter; Zihlmann, Simon; Baumgärtner, A.; Indolese, David I.; Watanabe, Kenji; Taniguchi, Takashi; Schönenberger, Christian

doi:10.1103/physrevlett.124.157701

Cited by 30 publications

(23 citation statements)

References 55 publications

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“…The charge neutrality point (CNP) occurs at a positive gate voltage. From a linear fit near the CNP we find a field effect charge carrier mobility of ∼130 000 cm 2 V −1 s −1 , independent of ∆z, suggesting a high device quality and that random strain fluctuations are probably not dominating scattering processes here [33]. The additional conductance minimum at V g ≈ −1.2 V may originate from a large contact doping due to the overlap of the electrodes with the graphene region near the edge contacts [34], or from a super-superlattice effect in encapsulated graphene when both the top and the bottom hBN layers are aligned to the graphene lattice [35].…”

mentioning

confidence: 67%

Global strain-induced scalar potential in graphene devices

Wang,

Baumgartner,

Makk

et al. 2020

Preprint

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By mechanically distorting a crystal lattice it is possible to engineer the electronic and optical properties of a material. In graphene, one of the major effects of such a distortion is an energy shift of the Dirac point, often described as a scalar potential. We demonstrate how such a scalar potential can be generated systematically over an entire electronic device and how the resulting changes in the graphene work function can be detected in transport experiments. Combined with Raman spectroscopy, we obtain a characteristic scalar potential consistent with recent theoretical estimates. This direct evidence for a scalar potential on a macroscopic scale due to deterministically generated strain in graphene paves the way for engineering the optical and electronic properties of graphene and similar materials by using external strain.

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confidence: 67%

Global strain-induced scalar potential in graphene devices

Wang,

Baumgartner,

Makk

et al. 2020

Preprint

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“…Studying the magnetoelectric effect in sBLG experimentally requires two components: (1) a technique to strain dual-gated BLG devices with electrical contacts and (2) a technique to detect the resultant magnetization. Recently, several experimental approaches have been reported to continuously and reversibly strain devices based on two-dimensional materials while maintaining well-performing electrical contacts [10,[54][55][56]. In MoS 2 [9,10], the magnetization was probed previously using magneto-optic imaging, but due to the small bandgap in BLG this is challenging to apply here.…”

Section: B Proposed Experimental Observationmentioning

confidence: 99%

Electrically tunable and reversible magnetoelectric coupling in strained bilayer graphene

Schaefer,

Nowack

2021

Preprint

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The valleys in hexagonal two-dimensional systems with broken inversion symmetry carry an intrinsic orbital magnetic moment. Despite this, such systems possess zero net magnetization unless additional symmetries are broken, since the contributions from both valleys cancel. A nonzero net magnetization can be induced through applying both uniaxial strain to break the rotational symmetry of the lattice and an in-plane electric field to break time-reversal symmetry owing to the resulting current. This creates a magnetoelectric effect whose strength is characterized by a magnetoelectric susceptibility, which describes the induced magnetization per unit applied in-plane electric field. Here, we predict the strength of this magnetoelectric susceptibility for Bernal-stacked bilayer graphene as a function of the magnitude and direction of strain, the chemical potential, and the interlayer electric field. We estimate that an orbital magnetization of 5400 µB/µm 2 can be achieved for 1 % uniaxial strain and a 10 µA bias current, which is almost three orders of magnitude larger than previously probed experimentally in strained monolayer MoS2. We also identify regimes in which the magnetoelectric susceptibility not only switches sign upon reversal of the interlayer electric field but also in response to small changes in the carrier density. Taking advantage of this reversibility, we further show that it is experimentally feasible to probe the effect using scanning magnetometry.

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“…S1). A recent study demonstrated that ripples and corrugations can be present in hBN-supported graphene devices, leading to random strain fluctuations (18). Importantly, these can be reduced by uniaxially straining the device, thereby leading to a charge carrier mobility enhancement.…”

Section: Room-temperature Characterizationmentioning

confidence: 99%

A Mechanically Tunable Quantum Dot in a Graphene Break Junction

Caneva¹,

Hermans²,

Lee³

et al. 2020

Nano Lett.

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Graphene quantum dots (QDs) are intensively studied as platforms for the next generation of quantum electronic devices. Fine tuning of the transport properties in monolayer graphene QDs, in particular with respect to the independent modulation of the tunnel barrier transparencies, remains challenging and is typically addressed using electrostatic gating. We investigate charge transport in back-gated graphene mechanical break junctions and reveal Coulomb blockade physics characteristic of a single, high-quality QD when a nanogap is opened in a graphene constriction. By mechanically controlling the distance across the newly-formed graphene nanogap, we achieve reversible tunability of the tunnel coupling to the drain electrode by five orders of magnitude, while keeping the source-QD tunnel coupling constant. These findings indicate that the tunnel coupling asymmetry can be significantly modulated with a mechanical tuning knob and has important implications for the development of future graphenebased devices, including energy converters and quantum calorimeters.

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Mobility Enhancement in Graphene by in situ Reduction of Random Strain Fluctuations

Cited by 30 publications

References 55 publications

Global strain-induced scalar potential in graphene devices

Global strain-induced scalar potential in graphene devices

Electrically tunable and reversible magnetoelectric coupling in strained bilayer graphene

A Mechanically Tunable Quantum Dot in a Graphene Break Junction

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