Boundary Modes from Periodic Magnetic and Pseudomagnetic Fields in Graphene

Phong, Võ Tiến; Mele, E. J.

doi:10.1103/physrevlett.128.176406

Cited by 18 publications

(18 citation statements)

References 41 publications

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“…The pseudo magnetic field can also stabilize nontrivial topological phase in graphene as was recently demonstrated in Ref. [36]. Experimentally, the narrow band in graphene under periodic strain was reported [37] and was investigated theoretically in Refs.…”

Section: Introductionmentioning

confidence: 77%

Nearly flat Chern band in periodically strained monolayer and bilayer graphene

Wan¹,

Sarkar²,

Sun³

et al. 2023

Preprint

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The flat band is a key ingredient for the realization of interesting quantum states for novel functionalities. In this work, we investigate the conditions for the flat band in both monolayer and bilayer graphene under periodic strain. We find topological nearly flat bands with homogeneous distribution of Berry curvature in both systems. The quantum metric of the nearly flat band closely resembles that for Landau levels. For monolayer graphene, the strain field can be regarded as an effective gauge field, while for Bernal-stacked (AB-stacked) bilayer graphene, its role is beyond the description of gauge field. We also provide an understanding of the origin of the nearly flat band in monolayer graphene in terms of the Jackiw-Rebbi model for Dirac fermions with sign-changing mass. Our work suggests strained graphene as a promising platform for strongly correlated quantum states.

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Section: Introductionmentioning

confidence: 77%

Nearly flat Chern band in periodically strained monolayer and bilayer graphene

Wan¹,

Sarkar²,

Sun³

et al. 2023

Preprint

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“…The chiral edge states and results of Hall conductance for Fermi levels inside the bulk gaps are expected to be robust against strain fluctuations and other sources of random disorder, provided the energy gaps of interest are not closed. Notice that, in contrast, the boundary modes in the absence of CPL 40 are fragile against such perturbations. The obtained topological quasi-flat bands might be promising platforms for exploring correlation-driven phenomena.…”

mentioning

confidence: 99%

“…The superlattice is oriented with its x-axis along the zigzag direction of graphene, and the superlattice constant a S ≫ a is chosen to be commensurate with that of graphene. 40 With these conventions, the height of the substrate surface is modeled by Next we look at the electronic properties, with a focus on the K valley (see SI for results in the K′ valley). The θ-dependent deformation profiles give rise to distinct patterns in band structures, total DOS, and LDOS at graphene sublattice sites A and B, as shown in Figure 2.…”

mentioning

confidence: 99%

“…A recent theoretical study found counterflowing in-gap boundary modes from the two valleys that reside on the same edge in a zigzag ribbon with periodic strain. 40 The presence of such boundary modes requires high-quality samples with zigzag edges to suppress intervalley scattering. Moreover, as no charge Hall response exists due to TRS, the experimental probe of these boundary modes is nontrivial.…”

mentioning

confidence: 99%

“…In addition, the samples can be easily investigated with local and nonlocal techniques under fixed strain configurations. Experiments using substrates to induce periodic deformations on graphene membranes have reported unexpected electronic transport − and peculiar local density of states (LDOS) features. , These developments were complemented by theoretical studies of effective models, which treat the effects of strain in terms of a pseudomagnetic field. − Although intriguing phenomena have been predicted, many of these works assume the pseudomagnetic field profile proposed in the particular setup of buckled graphene on NbSe 2 . One naturally expects that details of the pseudomagnetic field should depend on the specific experimental setting, i.e., strain profiles.…”

mentioning

confidence: 99%

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Topological Flat Bands in Strained Graphene: Substrate Engineering and Optical Control

2023

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The discovery of correlated phases in twisted moireś uperlattices accelerated the search for low-dimensional materials with exotic properties. A promising approach uses engineered substrates to strain the material. However, designing substrates for tailored properties is hindered by the incomplete understanding of the relationship between the substrate's shapes and the electronic properties of the deposited materials. By analyzing effective models of graphene under periodic deformations with generic crystalline profiles, we identify strong C 2z symmetry breaking as the critical substrate geometric feature for emerging energy gaps and quasi-flat bands. We find continuous strain profiles producing connected pseudomagnetic field landscapes are important for band topology. We show that the resultant electronic and topological properties from a substrate can be controlled with circularly polarized light, which also offers unique signatures for identifying the band topology imprinted by strain. Our results can guide experiments on strain engineering for exploring interesting transport and topological phenomena.

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Deep Learning on Atomistic Physical Fields of Graphene for Strain and Defect Engineering

Chang,

Zhu

2024

Advanced Intelligent Systems

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Strain and defect engineering have profound applications in two‐dimensional materials, where it is important to determine the equilibrated atomistic structures with defect conditions under mechanical deformations for computational materials design. Nevertheless, how to efficiently predict relaxed atomistic structures and the associated physical fields on each atom or bond under evolving mechanical deformations remains as an essential challenge. To address this issue, a deep neural network architecture is designed to embed the state of applied strains into the defect‐engineered atomistic geometry, so that deformation‐coupled physical fields of interests on atoms or bonds can be predicted or derived over continuous state of deformations. For demonstration, the combination of applied tensile strains and shear strain on monolayer graphene with random distribution of Stone–Wales defects and vacancy defects is considered. The unique advantage of this framework is the development of strain‐embedding concept combined with generative adversarial network, which can be feasibly extended to other material and other conditions. The computational approach sheds light on boosting the efficiency of evaluating physical properties of 2D materials under complex strain and defect states.

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Boundary Modes from Periodic Magnetic and Pseudomagnetic Fields in Graphene

Cited by 18 publications

References 41 publications

Nearly flat Chern band in periodically strained monolayer and bilayer graphene

Nearly flat Chern band in periodically strained monolayer and bilayer graphene

Topological Flat Bands in Strained Graphene: Substrate Engineering and Optical Control

Deep Learning on Atomistic Physical Fields of Graphene for Strain and Defect Engineering

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