Discovering Topological Surface States of Dirac Points

Cheng, Hengbin; Sha, Yi-Xin; Liu, Rongjuan; Fang, Chen; Lü, Ling

doi:10.1103/physrevlett.124.104301

Cited by 48 publications

(40 citation statements)

References 57 publications

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“…The design of our sonic crystal enables us to observe not only the hinge states in frequency-resolved spectroscopy but also their spatial localization in pressure-field distributions. Not only is this HO Dirac sonic crystal sharply different from the conventional solid-state Dirac semimetals that are characterized by surface Fermi arcs 3,16,17 , but it is also markedly different from the recently achieved non-symmorphic Dirac sonic crystals that feature symmetry-enforced Dirac points and quad-helicoid surface arcs 32,33 . Last but not at least, our scheme for achieving spinless 3D HO topological phases can be readily generalized to other classical wave systems such as photonic crystals with similar space groups.…”

Section: Co-dimensioncontrasting

confidence: 56%

Higher-order Dirac sonic crystals

Qiu

Xiao

et al. 2020

Preprint

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Discovering new topological phases of matter is a major theme in fundamental physics and materials science1,2. Dirac semimetal features isolated fourfold linear band crossings, i.e., Dirac points, and provides an exceptional platform for exploring topological phase transitions under symmetry breaking3. Recent theoretical studies4,5 have revealed that a three-dimensional Dirac semimetal can harbor fascinating hinge states, a high-order (HO) topological manifestation not known before. However, realization of such a HO Dirac phase in experiment is yet to be achieved, not to mention the fascinating hinge states, although candidate solid-state materials have been suggested5. Here we propose a minimum model to construct a spinless HO Dirac semimetal protected by C_6v symmetry. By breaking different symmetries, this parent phase transitions into a variety of novel topological phases including HO topological insulator, HO Weyl semimetal, and HO nodal-ring semimetal. Furthermore, for the first time, we experimentally realize this unprecedented HO topological phase in a sonic crystal and unambiguously present the smoking-gun observation of the desired hinge states via momentun-space spectroscopy and real-space visualization. Our findings may offer new opportunities to manipulate classical waves such as sound and light.

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Section: Co-dimensioncontrasting

confidence: 56%

Higher-order Dirac sonic crystals

Qiu

Xiao

et al. 2020

Preprint

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“…In addition, they are neighbors to many novel topological phases and thus serve as ideal platforms for investigating topological phase transitions 19 . Three-dimensional Dirac semimetals have been observed in both electronic systems and classical waves 19,[29][30][31] . In electronic systems, DNLSs are possible in the absence of spin-orbital couplings [16][17][18] .…”

Section: Introductionmentioning

confidence: 99%

Double-bowl state in photonic Dirac nodal line semimetal

Zhang

Jiang

et al. 2021

Light Sci Appl

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The past decade has seen a proliferation of topological materials for both insulators and semimetals in electronic systems and classical waves. Topological semimetals exhibit topologically protected band degeneracies, such as nodal points and nodal lines. Dirac nodal line semimetals (DNLS), which own four-fold line degeneracy, have drawn particular attention. DNLSs have been studied in electronic systems but there is no photonic DNLS. Here in this work, we provide a new mechanism, which is unique for photonic systems to investigate a stringent photonic DNLS. When truncated, the photonic DNLS exhibits double-bowl states (DBS), which comprise two sets of perpendicularly polarized surface states. In sharp contrast to nondegenerate surface states in other photonic systems, here the two sets of surface states are almost degenerate over the whole-spectrum range. The DBS and the bulk Dirac nodal ring (DNR) dispersion along the relevant directions, are experimentally resolved.

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“…The milestone of topological physics dates back to the discovery of quantum Hall phases, where 2D electron gas under a perpendicular magnetic field has quantized Hall conductance [28]. Because the magnetic field broke T, electrons in the quantum Hall effect propagate one way along the boundary, generating the chiral current.…”

Section: D Topological Semimetal Phasesmentioning

confidence: 99%

“…The number of gapless edge modes inside a bandgap is determined by the difference of gap Chern number, which is the summation of all band Chern numbers below the bandgap, also known as the bulk-edge correspondence. When T is broken with magnetic field, the photonic quantum Hall effect can also emerge in photonic crystals composed of magnetoelectric or gyromagnetic materials [14,15,[28][29][30]. The magnetoelectric materials have cross-coupling between electric and magnetic fields, where the constitutive relations take the form of D εE + χH and B μH + ζE.…”

Section: D Topological Semimetal Phasesmentioning

confidence: 99%

A Review of Topological Semimetal Phases in Photonic Artificial Microstructures

et al. 2021

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In the past few years, the concept of topological matter has inspired considerable research in broad areas of physics. In particular, photonic artificial microstructures like photonic crystals and metamaterials provide a unique platform to investigate topologically non-trivial physics in spin-1 electromagnetic fields. Three-dimensional (3D) topological semimetal band structures, which carry non-trivial topological charges, are fundamental to 3D topological physics. Here, we review recent progress in understanding 3D photonic topological semimetal phases and various approaches for realizing them, especially with photonic crystals or metamaterials. We review topological gapless band structures and topological surface states aroused from the non-trivial bulk topology. Weyl points, 3D Dirac points, nodal lines, and nodal surfaces of different types are discussed. We also demonstrate their application in coupling spin-polarized electromagnetic waves, anomalous reflection, vortex beams generation, bulk transport, and non-Hermitian effects.

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Discovering Topological Surface States of Dirac Points

Cited by 48 publications

References 57 publications

Higher-order Dirac sonic crystals

Higher-order Dirac sonic crystals

Double-bowl state in photonic Dirac nodal line semimetal

A Review of Topological Semimetal Phases in Photonic Artificial Microstructures

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