Edge states in a two-dimensional honeycomb lattice of massive magnetic skyrmions

Magnetic topological insulators (TIs), including the quantum anomalous Hall effect and antiferromagnetic TIs, have attracted significant attention owing to the exotic properties they give rise to, however, ferromagnetic TIs with gapless surface/edge states and a nonzero topological invariant have not been reported so far.

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Bulk-edge correspondence of classical diffusion phenomena

Scientific Reports ◽

10.1038/s41598-020-80180-w ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Tsuneya Yoshida ◽

Yasuhiro Hatsugai

Keyword(s):

Temperature Field ◽

Diffusion Equation ◽

Edge State ◽

Lattice System ◽

Honeycomb Lattice ◽

Two Dimensional ◽

Winding Number ◽

Edge States ◽

Diffusive Dynamics ◽

Diffusion Phenomena

AbstractWe elucidate that diffusive systems, which are widely found in nature, can be a new platform of the bulk-edge correspondence, a representative topological phenomenon. Using a discretized diffusion equation, we demonstrate the emergence of robust edge states protected by the winding number for one- and two-dimensional systems. These topological edge states can be experimentally accessible by measuring diffusive dynamics at edges. Furthermore, we discover a novel diffusion phenomenon by numerically simulating the distribution of temperatures for a honeycomb lattice system; the temperature field with wavenumber $$\pi $$ π cannot diffuse to the bulk, which is attributed to the complete localization of the edge state.

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Near- and Far-Field Excitation of Topological Plasmonic Metasurfaces

Photonics ◽

10.3390/photonics7040081 ◽

2020 ◽

Vol 7 (4) ◽

pp. 81

Author(s):

Matthew Proctor ◽

Xiaofei Xiao ◽

Richard V. Craster ◽

Stefan A. Maier ◽

Vincenzo Giannini ◽

...

Keyword(s):

Angular Momentum ◽

Honeycomb Lattice ◽

Far Field ◽

Two Dimensional ◽

Edge States ◽

Source Position ◽

Magnetic Dipoles ◽

Classical Wave ◽

Field Excitation ◽

Crystalline Symmetry

The breathing honeycomb lattice hosts a topologically non-trivial bulk phase due to the crystalline-symmetry of the system. Pseudospin-dependent edge states, which emerge at the interface between trivial and non-trivial regions, can be used for the directional propagation of energy. Using the plasmonic metasurface as an example system, we probe these states in the near- and far-field using a semi-analytical model. We provide the conditions under which directionality was observed and show that it is source position dependent. By probing with circularly-polarised magnetic dipoles out of the plane, we first characterise modes along the interface in terms of the enhancement of source emissions due to the metasurface. We then excite from the far-field with non-zero orbital angular momentum beams. The position-dependent directionality holds true for all classical wave systems with a breathing honeycomb lattice. Our results show that a metasurface in combination with a chiral two-dimensional material, could be used to guide light effectively on the nanoscale.

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Strain-Induced Quantum Spin Hall Effect in Two-Dimensional Methyl-Functionalized Silicene SiCH3

Nanomaterials ◽

10.3390/nano8090698 ◽

2018 ◽

Vol 8 (9) ◽

pp. 698 ◽

Cited By ~ 4

Author(s):

Ceng-Ceng Ren ◽

Wei-Xiao Ji ◽

Shu-Feng Zhang ◽

Chang-Wen Zhang ◽

Ping Li ◽

...

Keyword(s):

Hexagonal Boron Nitride ◽

Quantum Spin ◽

Honeycomb Lattice ◽

Potential Candidate ◽

Two Dimensional ◽

Edge States ◽

Spin Orbital ◽

Spintronic Devices ◽

Potential Applications ◽

Quantum Spin Hall

Quantum Spin Hall (QSH) has potential applications in low energy consuming spintronic devices and has become a researching hotspot recently. It benefits from insulators feature edge states, topologically protected from backscattering by time-reversal symmetry. The properties of methyl functionalized silicene (SiCH3) have been investigated using first-principles calculations, which show QSH effect under reasonable strain. The origin of the topological characteristic of SiCH3, is mainly associated with the s-pxy orbitals band inversion at Γ point, whilst the band gap appears under the effect of spin-orbital coupling (SOC). The QSH phase of SiCH3 is confirmed by the topological invariant Z2 = 1, as well as helical edge states. The SiCH3 supported by hexagonal boron nitride (BN) film makes it possible to observe its non-trivial topological phase experimentally, due to the weak interlayer interaction. The results of this work provide a new potential candidate for two-dimensional honeycomb lattice spintronic devices in spintronics.

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Theoretical realization of two-dimensional Dirac/Weyl line-node and traversing edge states in penta-X2Y monolayers

Applied Materials Today ◽

10.1016/j.apmt.2021.101057 ◽

2021 ◽

Vol 23 ◽

pp. 101057

Author(s):

Lirong Wang ◽

Lei Jin ◽

Guodong Liu ◽

Ying Liu ◽

Xuefang Dai ◽

...

Keyword(s):

Two Dimensional ◽

Edge States ◽

Line Node

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Robust zero modes in disordered two-dimensional honeycomb lattice with Kekulé bond ordering

Annals of Physics ◽

10.1016/j.aop.2021.168440 ◽

2021 ◽

pp. 168440

Author(s):

Tohru Kawarabayashi ◽

Yuya Inoue ◽

Ryo Itagaki ◽

Yasuhiro Hatsugai ◽

Hideo Aoki

Keyword(s):

Honeycomb Lattice ◽

Two Dimensional ◽

Zero Modes

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Schwarzian quantum mechanics as a Drinfeld-Sokolov reduction of BF theory

Journal of High Energy Physics ◽

10.1007/jhep12(2020)189 ◽

2020 ◽

Vol 2020 (12) ◽

Author(s):

Fridrich Valach ◽

Donald R. Youmans

Keyword(s):

Quantum Mechanics ◽

Partition Function ◽

Gauge Group ◽

Path Integral ◽

Coadjoint Orbits ◽

Two Dimensional ◽

Edge States ◽

Class Constraint ◽

Action Functional ◽

Bf Theory

Abstract We give an interpretation of the holographic correspondence between two-dimensional BF theory on the punctured disk with gauge group PSL(2, ℝ) and Schwarzian quantum mechanics in terms of a Drinfeld-Sokolov reduction. The latter, in turn, is equivalent to the presence of certain edge states imposing a first class constraint on the model. The constrained path integral localizes over exceptional Virasoro coadjoint orbits. The reduced theory is governed by the Schwarzian action functional generating a Hamiltonian S1-action on the orbits. The partition function is given by a sum over topological sectors (corresponding to the exceptional orbits), each of which is computed by a formal Duistermaat-Heckman integral.

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Experimental Realization and Phase Engineering of a Two-Dimensional SnSb Binary Honeycomb Lattice

ACS Nano ◽

10.1021/acsnano.1c05583 ◽

2021 ◽

Author(s):

Heping Li ◽

Dechun Zhou ◽

Qingyuan He ◽

Nan Si ◽

Benwu Xin ◽

...

Keyword(s):

Honeycomb Lattice ◽

Two Dimensional ◽

Experimental Realization ◽

Phase Engineering

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Extremely flat band in bilayer graphene

Science Advances ◽

10.1126/sciadv.aau0059 ◽

2018 ◽

Vol 4 (11) ◽

pp. eaau0059 ◽

Cited By ~ 33

Author(s):

D. Marchenko ◽

D. V. Evtushinsky ◽

E. Golias ◽

A. Varykhalov ◽

Th. Seyller ◽

...

Keyword(s):

Elevated Temperatures ◽

Bilayer Graphene ◽

Flat Band ◽

Honeycomb Lattice ◽

Band Model ◽

Two Dimensional ◽

Band Formation ◽

Constant Energy ◽

Mexican Hat ◽

Band Dispersion

We propose a novel mechanism of flat band formation based on the relative biasing of only one sublattice against other sublattices in a honeycomb lattice bilayer. The mechanism allows modification of the band dispersion from parabolic to “Mexican hat”–like through the formation of a flattened band. The mechanism is well applicable for bilayer graphene—both doped and undoped. By angle-resolved photoemission from bilayer graphene on SiC, we demonstrate the possibility of realizing this extremely flattened band (< 2-meV dispersion), which extends two-dimensionally in a k-space area around the K¯ point and results in a disk-like constant energy cut. We argue that our two-dimensional flat band model and the experimental results have the potential to contribute to achieving superconductivity of graphene- or graphite-based systems at elevated temperatures.

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