Two-Dimensional Quadrupole Topological Insulator in γ-Graphyne

Liu, Bing; Zhao, Gan; Liu, Zhao; Wang, Z. F.

doi:10.1021/acs.nanolett.9b02719

Cited by 109 publications

(72 citation statements)

References 45 publications

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“…The existence of one-dimensional hinge states has been experimentally confirmed in bismuth [60] and multi-layer WTe 2 [61]. In 2D higher-order TIs, one-dimensional edges are insulating whereas the cor-ners between different edges can host zero-dimensional ingap states that are isolated from both edge and bulk bands by an energy gap [53][54][55][62][63][64][65]. In contrast to the gapless edge states in conventional topological insulators, higherorder topological corner states are not conducting and behave like localized bound states.…”

Section: Introductionmentioning

confidence: 93%

Transport induced dimer state from topological corner states

Wang

Ren

et al. 2021

Sci. China Phys. Mech. Astron.

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Recently, a new type of second-order topological insulator has been theoretically proposed by introducing an in-plane Zeeman field into the Kane-Mele model in the two-dimensional honeycomb lattice. A pair of topological corner states arise at the corners with obtuse angles of an isolated diamond-shaped flake. To probe the corner states, we study their transport properties by attaching two leads to the system. Dressed by incoming electrons, the dynamic corner state is very different from its static counterpart. Resonant tunneling through the dressed corner state can occur by tuning the in-plane Zeeman field. At the resonance, the pair of spatially well separated and highly localized corner states can form a dimer state, whose wavefunction extends almost the entire bulk of the diamond-shaped flake. By varying the Zeeman field strength, multiple resonant tunneling events are mediated by the same dimer state. This re-entrance effect can be understood by a simple model. These findings extend our understanding of dynamic aspects of the second-order topological corner states.

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Section: Introductionmentioning

confidence: 93%

Transport induced dimer state from topological corner states

Wang

Ren

et al. 2021

Sci. China Phys. Mech. Astron.

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“…Figure 3l depicts the profile of corner states, demonstrating their confinement to the corners of the crystal. Other realizations of higher-order TIs have been reported in [332][333][334][335][336][337][338][339][340][341][342][343][344][345][346].…”

Section: Higher-order Topological Insulatorsmentioning

confidence: 99%

Topological wave insulators: a review

Zangeneh-Nejad¹,

Alù²,

Fleury³

2020

Comptes Rendus. Physique

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Originally discovered in condensed matter systems, topological insulators (TIs) have been ubiquitously extended to various fields of classical wave physics including photonics, phononics, acoustics, mechanics, and microwaves. In the bulk, like any other insulator, electronic TIs exhibit an excessively high resistance to the flow of mobile charges, prohibiting metallic conduction. On their surface, however, they support one-way conductive states with inherent protection against certain types of disorder and defects, defying the common physical wisdom of electronic transport in presence of impurities. When transposed to classical waves, TIs open a wealth of exciting engineering-oriented applications, such as robust routing, lasing, signal processing, switching, etc., with unprecedented robustness against various classes of defects. In this article, we first review the basic concept of topological order applied to classical waves, starting from the simple onedimensional example of the Su-Schrieffer-Heeger (SSH) model. We then move on to two-dimensional wave TIs, discussing classical wave analogues of Chern, quantum Hall, spin-Hall, Valley-Hall, and Floquet TIs. Finally, we review the most recent developments in the field, including Weyl and nodal semimetals, higherorder topological insulators, and self-induced non-linear topological states.

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“…However, like most higher-order topological states, a material realization of the state is still missing. Currently, the research on higher-order topology is severely hindered by the lack of realistic material candidates 32,[40][41][42][43][44][45][46][47][48] : the only experimentally verified second-order topological insulator material so far is Bi 32 , and features of combined higher-order and weak topol-ogy were reported in Bi 2 TeI 49 . Thus, it is an outstanding challenge to search for suitable existing materials that realize the second-order nodal-line semimetal state.…”

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confidence: 99%

Second-Order Real Nodal-Line Semimetal in Three-Dimensional Graphdiyne

Chen,

Zeng,

Chen

et al. 2021

Preprint

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Real topological phases featuring real Chern numbers and second-order boundary modes have been a focus of current research, but finding their material realization remains a challenge. Here, based on first-principles calculations and theoretical analysis, we reveal the already experimentally synthesized three-dimensional (3D) graphdiyne as the first realistic example of the recently proposed second-order real nodal-line semimetal. We show that the material hosts a pair of real nodal rings, each protected by two topological charges: a real Chern number and a 1D winding number. The two charges generate distinct topological boundary modes at distinct boundaries. The real Chern number leads to a pair of hinge Fermi arcs, whereas the winding number protects a double drumhead surface bands. We develop a low-energy model for 3D graphdiyne which captures the essential topological physics. Experimental aspects and possible topological transition to a 3D real Chern insulator phase are discussed.

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Two-Dimensional Quadrupole Topological Insulator in γ-Graphyne

Cited by 109 publications

References 45 publications

Transport induced dimer state from topological corner states

Transport induced dimer state from topological corner states

Topological wave insulators: a review

Second-Order Real Nodal-Line Semimetal in Three-Dimensional Graphdiyne

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