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

Mahmud, Md Tareq; Zhai, Dawei; Sandler, Nancy

doi:10.1021/acs.nanolett.3c02513

Cited by 11 publications

(4 citation statements)

References 75 publications

(117 reference statements)

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“…Here, we consider a substrate-induced buckling transition that gives rise to a periodic height profile with

symmetry. In the first-star approximation, the height profile is given by

with

, where the phase

controls the shape of the profile ( 8 , 30 – 32 ). Experimentally,

can be tuned by designing different artificial substrates.…”

Section: Materials Systemsmentioning

confidence: 99%

Roses in the nonperturbative current response of artificial crystals

De Beule,

Phong,

Mele

2023

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

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In two-dimensional artificial crystals with large real-space periodicity, the nonlinear current response to a large applied electric field can feature a strong angular dependence, which encodes information about the band dispersion and Berry curvature of isolated electronic Bloch minibands. Within the relaxation-time approximation, we obtain analytic expressions up to infinite order in the driving field for the current in a band-projected theory with time-reversal and trigonal symmetry. For a fixed field strength, the dependence of the current on the direction of the applied field is given by rose curves whose petal structure is symmetry constrained and is obtained from an expansion in real-space translation vectors. We illustrate our theory with calculations on periodically buckled graphene and twisted double bilayer graphene, wherein the discussed physics can be accessed at experimentally relevant field strengths.

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“…Here, we consider a substrate-induced buckling transition that gives rise to a periodic height profile with

symmetry. In the first-star approximation, the height profile is given by

with

, where the phase

controls the shape of the profile ( 8 , 30 – 32 ). Experimentally,

can be tuned by designing different artificial substrates.…”

Section: Materials Systemsmentioning

confidence: 99%

Roses in the nonperturbative current response of artificial crystals

De Beule,

Phong,

Mele

2023

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

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“…For this reason, alternative systems are currently being explored to preserve flat bands without relying solely on the rotation angle. Examples of these systems include graphene subjected to mechanical deformations [21][22][23][24][25][26][27][28][29] , multilayer graphene twisted (MTLG) under pressure [30][31][32][33][34], cyclicgraphyne, cyclicgraphdiyne [35] and holey graphene (HG) [36][37][38][39], where the theoretical possibility of chiral superconductivity emergence has been demonstrated [40].…”

Section: Introductionmentioning

confidence: 99%

Flat bands without twists: periodic holey graphene

de Jesús Espinosa-Champo,

Naumis

2024

J. Phys.: Condens. Matter

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\textit{Holey Graphene} (HG) is a widely used graphene material for the synthesis of high-purity and highly crystalline materials. The electronic properties of a periodic distribution of lattice holes are explored here, demonstrating the emergence of flat bands. It is established that such flat bands arise as a consequence of an induced sublattice site imbalance, i.e., by having more sites in one of the graphene's bipartite sublattice than in the other. This is equivalent to the breaking of a path-exchange symmetry. By further breaking the inversion symmetry, gaps and a nonzero Berry curvature are induced, leading to topological bands. In particular, the folding of the Dirac cones from the hexagonal Brillouin zone (BZ) to the holey superlattice rectangular BZ of HG, with sizes proportional to an integer $n$ times the graphene's lattice parameter, leads to a periodicity in the gap formation such that $n \equiv 0$ (mod $3$). A low-energy hamiltonian for the three central bands is also obtained revealing that the system behaves as an effective $\alpha-\mathcal{T}_{3}$ graphene material. Therefore, a simple protocol is presented here that allows for obtaining flat bands at will. Such bands are known to increase electron-electron correlation effects. Therefore, the present work provides an alternative system that is much easier to build than twisted systems, allowing for the production of flat bands and potentially highly correlated quantum phases.

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“…27 These properties play an important role in shaping the electronic and optoelectronic performance of 2D materials. 28–33 The adhesion energies of 2D materials to substrates, for example, have been reported in various materials: 6 to 28 meV Å −2 for graphene on silicon oxide, 6,34–37 9.4 meV Å −2 for graphene on silicon, 38,39 1.12 meV Å −2 for MoS 2 on PMDS, 40 6.3 meV Å −2 for MoS 2 on Al 2 O 3 , 41 and 5 meV Å −2 for MoS 2 on SiO 2 . 41 Studies on the folding behavior of 2D materials, 42 and investigations of heterostructures involving 2D materials, 43 provide valuable information on their mechanical characteristics.…”

Section: Introductionmentioning

confidence: 99%