Stacking domain morphology in epitaxial graphene on silicon carbide

Jong, Tobias A. de; Visser, Luuk; Jobst, Johannes; Tromp, R. M.; Molen, Sense Jan van der

doi:10.1103/physrevmaterials.7.034001

Cited by 6 publications

(1 citation statement)

References 51 publications

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“…The soliton length of about a M = 250 nm gives an estimate of

{\varepsilon}_{\mathrm{bi}}=({a}_{\mathrm{b}}-{a}_{\mathrm{t}})/{a}_{\mathrm{t}}={a}_{\mathrm{Gr}}/{a}_{\mathrm{M}}\approx 0.1\%

where a t = a Gr is the lattice constant of the top layer assumed to be unstrained and a b is the lattice constant of the bottom layer. This value is consistent with previous measurements [ 26–28 ] which concluded that strain is imposed to the bottom layer by the

6\sqrt {3}\times 6\sqrt {3}R30^\circ

SiC reconstruction.…”

Section: Resultssupporting

confidence: 93%

Giant Atomic Swirl in Graphene Bilayers with Biaxial Heterostrain

Mesple,

Walet,

Trambly de Laissardière

et al. 2023

Advanced Materials

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The study of moiré engineering started with the advent of van der Waals heterostructures in which stacking two‐dimensional layers with different lattice constants leads to a moiré pattern controlling their electronic properties. The field entered a new era when it was found that adjusting the twist between two graphene layers led to strongly‐correlated‐electron physics and topological effects associated with atomic relaxation. Twist is now used routinely to adjust the properties of two‐dimensional materials. Here, we investigate a new type of moiré superlattice in bilayer graphene when one layer is biaxially strained with respect to the other ‐ so‐called biaxial heterostrain. Scanning tunneling microscopy measurements uncover spiraling electronic states associated with a novel symmetry‐breaking atomic reconstruction at small biaxial heterostrain. Atomistic calculations using experimental parameters as inputs reveal that a giant atomic swirl forms around regions of aligned stacking to reduce the mechanical energy of the bilayer. Tight‐binding calculations performed on the relaxed structure show that the observed electronic states decorate spiraling domain wall solitons as required by topology. This study establishes biaxial heterostrain as an important parameter to be harnessed for the next step of moiré engineering in van der Waals multilayers.This article is protected by copyright. All rights reserved

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“…The soliton length of about a M = 250 nm gives an estimate of

{\varepsilon}_{\mathrm{bi}}=({a}_{\mathrm{b}}-{a}_{\mathrm{t}})/{a}_{\mathrm{t}}={a}_{\mathrm{Gr}}/{a}_{\mathrm{M}}\approx 0.1\%

6\sqrt {3}\times 6\sqrt {3}R30^\circ

SiC reconstruction.…”

Section: Resultssupporting

confidence: 93%

Giant Atomic Swirl in Graphene Bilayers with Biaxial Heterostrain

Mesple,

Walet,

Trambly de Laissardière

et al. 2023

Advanced Materials

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Designing Moiré Patterns by Shearing

Pantaleón,

Sainz-Cruz,

Guinea

2024

ACS Nano

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We analyze the elastic properties, structural effects, and low-energy physics of a sheared nanoribbon placed on top of graphene, which creates a gradually changing moiré pattern. By means of a classical elastic model we derive the strains in the ribbon and we obtain its electronic energy spectrum with a scaled tight-binding model. The size of the sheared region is determined by the balance between elastic and van der Waals energy, and different regimes are identified. Near the clamped edge, moderate strains and small twist angles lead to one-dimensional channels. Near the sheared edge, a long region behaves like magic angle twisted bilayer graphene (TBG), showing a sharp peak in the density of states, mostly isolated from the rest of the spectrum. We also calculate the band topology along the ribbon and we find that it is stable for large intervals of strains and twist angles. Together with the experimental observations, these results show that the sheared nanoribbon geometry is ideal for exploring superconductivity and correlated phases in TBG in the very sought-after regime of ultralow twist angle disorder.

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Spontaneous emergence of straintronics effects and striped stacking domains in untwisted three-layer epitaxial graphene

Rejhon,

Parashar,

Schellack

et al. 2024

Proc. Natl. Acad. Sci. U.S.A.

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Emergent electronic phenomena, from superconductivity to ferroelectricity, magnetism, and correlated many-body band gaps, have been observed in domains created by stacking and twisting atomic layers of Van der Waals materials. In graphene, emergent properties have been observed in ABC stacking domains obtained by exfoliation followed by expert mechanical twisting and alignment with the desired orientation, a process very challenging and nonscalable. Here, conductive atomic force microscopy shows in untwisted epitaxial graphene grown on SiC the surprising presence of striped domains with dissimilar conductance, a contrast that demonstrates the presence of ABA and ABC domains since it matches exactly the conductivity difference observed in ABA/ABC domains in twisted exfoliated graphene and calculated by density functional theory. The size and geometry of the stacking domains depend on the interplay between strain, solitons crossing, and shape of the three-layer regions. Interestingly, we demonstrate the growth of three-layer regions in which the ABA/ABC stacking domains self-organize in stable stripes of a few tens of nanometers. The growth-controlled production of isolated and stripe-shaped ABA/ABC domains open the path to fabricate quantum devices on these domains. These findings on self-assembly formation of ABA/ABC epitaxial graphene stripes on SiC without the need of time-consuming and nonscalable graphene exfoliation, alignment, and twisting provide different potential applications of graphene in electronic devices.

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Stacking domain morphology in epitaxial graphene on silicon carbide

Cited by 6 publications

References 51 publications

Giant Atomic Swirl in Graphene Bilayers with Biaxial Heterostrain

Giant Atomic Swirl in Graphene Bilayers with Biaxial Heterostrain

Designing Moiré Patterns by Shearing

Spontaneous emergence of straintronics effects and striped stacking domains in untwisted three-layer epitaxial graphene

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