Emergent Gauge Fields from Curvature in Single Layers of Transition-Metal Dichalcogenides

Ochoa, Héctor; Zarzuela, Ricardo; Tserkovnyak, Yaroslav

doi:10.1103/physrevlett.118.026801

Cited by 30 publications

(32 citation statements)

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“…Subsequently, many experimental confirmations of the pseudomagnetic fields in graphene have been reported under other strain configurations [260][261][262][263][264][265][266][267][268] and in various graphene-like systems such as molecular graphene [203], photonic crystals [269], and optical lattices [270]. Beyond graphene, strain-induced gauge fields have been also characterized on bilayer graphene [271][272][273], borophene [274], topological insulators [275], transition metal dichalcogenides [9,276,277] and on three-dimensional Dirac and Weyl semimetals [166,243,[278][279][280].…”

Section: Nonuniform Strain: Gauge Fields and Positiondependent Fermi mentioning

confidence: 99%

Electronic and optical properties of strained graphene and other strained 2D materials: a review

et al. 2017

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Abstract. This review presents the state of the art in strain and rippleinduced effects on the electronic and optical properties of graphene. It starts by providing the crystallographic description of mechanical deformations, as well as the diffraction pattern for different kinds of representative deformation fields. Then, the focus turns to the unique elastic properties of graphene, and to how strain is produced. Thereafter, various theoretical approaches used to study the electronic properties of strained graphene are examined, discussing the advantages of each. These approaches provide a platform to describe exotic properties, such as a fractal spectrum related with quasicrystals, a mixed DiracSchrödinger behavior, emergent gravity, topological insulator states, in molecular graphene and other 2D discrete lattices. The physical consequences of strain on the optical properties are reviewed next, with a focus on the Raman spectrum. At the same time, recent advances to tune the optical conductivity of graphene by strain engineering are given, which open new paths in device applications. Finally, a brief review of strain effects in multilayered graphene and other promising 2D materials like silicene and materials based on other group-IV elements, phosphorene, dichalcogenide-and monochalcogenide-monolayers is presented, with a brief discussion of interplays among strain, thermal effects, and illumination in the latter material family.

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Section: Nonuniform Strain: Gauge Fields and Positiondependent Fermi mentioning

confidence: 99%

Electronic and optical properties of strained graphene and other strained 2D materials: a review

et al. 2017

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“…Conventional approaches for modeling can be classified in two categories: The top-down method treats the deformed layers as a manifold with curvature and local metric tensor structure, analogous to a membrane in soft matter 24 and to general relativity in curved space-time 25 . In this approach, once the differential geometry tensors are constructed from the deformed layers, they couple to the low energy effective field theories as symmetryallowed gauge fields, potentials and connections [26][27][28][29][30] . The bottom-up approach relies on computationally demanding first-principles calculations 31 or on scaling of tight-binding matrix elements in the presence of the lattice deformation 1,32,33 .…”

Section: Introductionmentioning

confidence: 99%

Electronic structure theory of strained two-dimensional materials with hexagonal symmetry

et al. 2018

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We derive electronic tight-binding Hamiltonians for strained graphene, hexagonal boron nitride and transition metal dichalcogenides based on Wannier transformation of ab initio density functional theory calculations. Our microscopic models include strain effects to leading order that respect the hexagonal crystal symmetry and local crystal configuration, and are beyond the central force approximation which assumes only pair-wise distance dependence. Based on these models, we also derive and analyze the effective low-energy Hamiltonians. Our ab initio approaches complement the symmetry group representation construction for such effective low-energy Hamiltonians and provide the values of the coefficients for each symmetry-allowed term. These models are relevant for the design of electronic device applications, since they provide the framework for describing the coupling of electrons to other degrees of freedom including phonons, spin and the electromagnetic field. The models can also serve as the basis for exploring the physics of many-body systems of interesting quantum phases. PACS numbers: 71.15.-m, 73.22.-f, 74.78.Fk, arXiv:1709.07510v2 [cond-mat.mes-hall] 12 Aug 2018 0.273 −0.043 0.720 0.270 0.004 0.829 0.487 0.036 1.586 0.482 −0.022 1.507

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“…The notable transformation of the electronic properties of transition‐metal dichalcogenides (TMDs) when reduced to a single X–M–X plane (X: chalcogen; M: metal) makes them suitable for flexible, innovative optoelectronic devices, and transistors . Like graphene, few‐layer TMDs can also withstand surprisingly large mechanical deformations, which, coupled to the material's electronic structure, would enable the observation of nondissipative topological transport, provided a periodic modulation of strain is attained . TMD monolayers (MLs) and nanostructures are also important for their catalytic role in the cost‐effective production of hydrogen .…”

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confidence: 99%

“…The detailed knowledge of the evolution of the strain tensor across the domes' surface is particularly relevant since strain is known to alter profoundly the electronic properties—and hence the optical and transport properties—of TMDs, which can lead to, e.g., the emergence of giant pseudo‐magnetic fields and to the generation of persistent currents . For this to happen, specific and stable configurations of the strain field need be achieved, and spatial control and durability are therefore necessary.…”

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confidence: 99%

“…Therefore, their deposition on top of bulk TMD samples before proton irradiation should not hinder the dome formation process, and the controlled formation of (ordered) TMD domes could thus be exploited to define a template for modulating strain in a much wider range of 2D materials, leading, e.g., to the emergence of giant pseudo‐magnetic fields in graphene. Thanks to the spatial control enabled by our method, these latter could be created in the desired periodic configurations, which have been predicted to result in the generation of dissipation‐less electrical currents …”

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Controlled Micro/Nanodome Formation in Proton‐Irradiated Bulk Transition‐Metal Dichalcogenides

et al. 2019

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The notable transformation of the electronic properties of transition-metal dichalcogenides (TMDs) when reduced to a single X-M-X plane (X: chalcogen; M: metal) [1] makes them suitable for flexible, innovative optoelectronic devices, [2][3][4] and transistors. [5] Like graphene, few-layer TMDs can also withstand surprisingly large mechanical deformations, [6][7][8][9] which, coupled to the material's electronic structure, would enable the observation of nondissipative topological transport, provided a periodic modulation of strain is attained. [10][11][12][13] TMD monolayers (MLs) and nanostructures are also important for their catalytic role in the cost-effective production of hydrogen. [14][15][16] These examples share the need to achieve spatial control of the material's properties, over sample regions with size ranging from the nano [14,16] to the micrometer [16] scale lengths.In this study, we present a route toward the patterning of TMDs based on the effects of low-energy proton irradiation [17] on the structural and electronic properties of bulk WS 2 , WSe 2 , WTe 2 , MoS 2 , MoSe 2 , and MoTe 2 . Suitable irradiation conditions trigger the production and accumulation of H 2 just beneath the first X-M-X basal plane, leading to the localized exfoliation of the topmost monolayer and to the formation of spherically shaped domes. Structural and optical characterizations confirm that these domes are typically one ML-thick and contain H 2 at pressures in the 10-100 atm range, depending on their size. Such high pressures induce strong and complex strain fields acting on the curved X-M-X planes, that are evaluated by means of a mechanical model. The domes' morphological characteristics can be tuned by lithographically controlling the area of the sample basal plane participating in the hydrogen production process. This results in the unprecedented fabrication of robust domes with controlled position/density and sizes tunable from the nanometer to the micrometer scale, that, by virtue of their inherently strained nature and geometry, might prompt a variety of applications.The samples, consisting of thick (tens to hundreds of MLs) TMD flakes, were obtained by mechanical exfoliation, deposited on Si substrates, and afterwards proton-irradiated using a Kaufman source (see the Experimental Methods). Differently from the other works in the literature concerning protonirradiation of TMDs-where beams with energies ≥10 5 eV are used, [18] aiming at the controlled formation of defects in the irradiated samples-here we irradiate the flakes with low energy At the few-atom-thick limit, transition-metal dichalcogenides (TMDs) exhibit strongly interconnected structural and optoelectronic properties. The possibility to tailor the latter by controlling the former is expected to have a great impact on applied and fundamental research. As shown here, proton irradiation deeply affects the surface morphology of bulk TMD crystals. Protons penetrate the top layer, resulting in the production and progressive accumulation of molecular hydr...

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Emergent Gauge Fields from Curvature in Single Layers of Transition-Metal Dichalcogenides

Cited by 30 publications

References 44 publications

Electronic and optical properties of strained graphene and other strained 2D materials: a review

Electronic and optical properties of strained graphene and other strained 2D materials: a review

Electronic structure theory of strained two-dimensional materials with hexagonal symmetry

Controlled Micro/Nanodome Formation in Proton‐Irradiated Bulk Transition‐Metal Dichalcogenides

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