Global Control of Stacking-Order Phase Transition by Doping and Electric Field in Few-Layer Graphene

Li, Hongyuan; Utama, M. Iqbal Bakti; Wang, Sheng; Zhao, Wenyu; Zhao, Sihan; Xiao, Xiao; Jiang, Yue; Jiang, Lili; Taniguchi, Takashi; Watanabe, Kenji; Weber‐Bargioni, Alexander; Zettl, Alex; Wang, Feng

doi:10.1021/acs.nanolett.9b05092

Cited by 45 publications

(66 citation statements)

References 28 publications

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“…At a small twist angle, the lattice energetically prefers to relax into triangular domains with alternating domains of ABAB and ABCA as a result of the atomic reconstruction. 16,27 Figure 1c shows an amplitude image from single-frequency LPFM that is consistent with those reported by McGilly et al 19 Although single-frequency LPFM can give reliable images on flat surfaces, it can also be sensitive to artifacts, 28 many of which are associated with shifts in the contact resonance frequency induced by the change in tip-sample contact stiffness leading to common misinterpretations of single-frequency measurements. 29 Accordingly, we also imaged the sample using dual-AC-resonance-tracking (DART) mode LPFM.…”

Section: Resultssupporting

confidence: 79%

“…Both the amplitude (Figure 2b) and phase images (Figure 2c) show moiré superlattices with separated domains and domain walls, consistent with the expected atomic reconstruction. 16,27 According to previous reports, ABAB domains should have lower energy compared with the ABCA domains, leading to the bending of domain walls into ABCA domains, with the resulting concave ABCA domains. 14,27 In Figures 2b-c the dashed white curves outline the ABAB and ABCA domains where ABAB is convex while ABCA is concave.…”

Section: Resultsmentioning

confidence: 91%

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Imaging Graphene Moiré Superlattices via Scanning Kelvin Probe Microscopy

Giridharagopal

et al. 2021

Nano Lett.

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Moiré superlattices in van der Waals heterostructures are gaining increasing attention because they offer new opportunities to tailor and explore unique electronic phenomena when stacking 2D materials with small twist angles. Here, we reveal local surface potentials associated with stacking domains in twisted double bilayer graphene (TDBG) moiré superlattices. Using a combination of both lateral Piezoresponse Force Microscopy (LPFM) and Scanning Kelvin Probe Microscopy (SKPM), we distinguish between Bernal (ABAB) and rhombohedral (ABCA) stacked graphene and directly correlate these stacking configurations with local surface potential. We find that the surface potential of the ABCA domains is ~15 mV higher (smaller work function) than that of the ABAB domains. First-principles calculations based on density functional theory further show that the different work functions between ABCA and ABAB domains arise from the stacking-dependent electronic structure. We show that, while the moiré superlattice visualized by LPFM can change with time, imaging the surface potential distribution via SKPM appears more stable, enabling the mapping of ABAB and ABCA domains without tip-sample contact-induced effects. Our results provide a new means to visualize and probe local domain stacking in moiré superlattices along with its impact on electronic properties.

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Section: Resultssupporting

confidence: 79%

Section: Resultsmentioning

confidence: 91%

Imaging Graphene Moiré Superlattices via Scanning Kelvin Probe Microscopy

Giridharagopal

et al. 2021

Nano Lett.

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“…The moiré period from fast Fourier transform (FFT; Fig. 2A, inset) is determined to At near-0° twist, the lattice energetically prefers to reconstruct into relaxed triangular domains with an alternating stacking sequence (14,38,39). In twisted trilayer graphene (tTG) and tetralayer tDBG, these domains correspond to Bernal (ABA and ABAB) and rhombohedral stacking (ABC and ABCA), respectively.…”

Section: Resultsmentioning

confidence: 99%

Ultrahigh-resolution scanning microwave impedance microscopy of moiré lattices and superstructures

et al. 2020

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Two-dimensional heterostructures composed of layers with slightly different lattice vectors exhibit new periodic structure known as moiré lattices, which, in turn, can support novel correlated and topological phenomena. Moreover, moiré superstructures can emerge from multiple misaligned moiré lattices or inhomogeneous strain distributions, offering additional degrees of freedom in tailoring electronic structure. High-resolution imaging of the moiré lattices and superstructures is critical for understanding the emerging physics. Here, we report the imaging of moiré lattices and superstructures in graphene-based samples under ambient conditions using an ultrahigh-resolution implementation of scanning microwave impedance microscopy. Although the probe tip has a gross radius of ~100 nm, spatial resolution better than 5 nm is achieved, which allows direct visualization of the structural details in moiré lattices and the composite super-moiré. We also demonstrate artificial synthesis of novel superstructures, including the Kagome moiré arising from the interplay between different layers.

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“…Previous reports have shown that applying molecular absorption or an external electric field can drive the stacking order transition and generate domain wall motion in graphene layers 17,22,23 . There is inevitable residue on graphene with molecular doping, which hinders the properties of graphene.…”

Section: Introductionmentioning

confidence: 99%

Light-induced irreversible structural phase transition in trilayer graphene

et al. 2020

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A crystal structure has a profound influence on the physical properties of the corresponding material. By synthesizing crystals with particular symmetries, one can strongly tune their properties, even for the same chemical configuration (compare graphite and diamond, for instance). Even more interesting opportunities arise when the structural phases of crystals can be changed dynamically through external stimulations. Such abilities, though rare, lead to a number of exciting phenomena, such as phase-change memory effects. In the case of trilayer graphene, there are two common stacking configurations (ABA and ABC) that have distinct electronic band structures and exhibit very different behaviors. Domain walls exist in the trilayer graphene with both stacking orders, showing fascinating new physics such as the quantum valley Hall effect. Extensive efforts have been dedicated to the phase engineering of trilayer graphene. However, the manipulation of domain walls to achieve precise control of local structures and properties remains a considerable challenge. Here, we experimentally demonstrate that we can switch from one structural phase to another by laser irradiation, creating domains of different shapes in trilayer graphene. The ability to control the position and orientation of the domain walls leads to fine control of the local structural phases and properties of graphene, offering a simple but effective approach to create artificial two-dimensional materials with designed atomic structures and electronic and optical properties.

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Global Control of Stacking-Order Phase Transition by Doping and Electric Field in Few-Layer Graphene

Cited by 45 publications

References 28 publications

Imaging Graphene Moiré Superlattices via Scanning Kelvin Probe Microscopy

Imaging Graphene Moiré Superlattices via Scanning Kelvin Probe Microscopy

Ultrahigh-resolution scanning microwave impedance microscopy of moiré lattices and superstructures

Light-induced irreversible structural phase transition in trilayer graphene

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