scholarly journals Quenching in Chern insulators with satellite Dirac points: The fate of edge states

2017 ◽  
Vol 95 (14) ◽  
Author(s):  
Utso Bhattacharya ◽  
Joanna Hutchinson ◽  
Amit Dutta
Keyword(s):  
Edge States ◽  
Chern Insulators

Non-Dirac Chern insulators with large band gaps and spin-polarized edge states

Nanoscale ◽  
2018 ◽  
Vol 10 (18) ◽  
pp. 8569-8577 ◽  
Author(s):  
Y. Xue ◽  
J. Y. Zhang ◽  
B. Zhao ◽  
X. Y. Wei ◽  
Z. Q. Yang
Keyword(s):  
Band Gap ◽  
Band Gaps ◽  
Edge States ◽  
Half Metallic ◽  
Spin Polarized ◽  
Chern Insulators

A non-Dirac Chern insulator with a large band gap (244 meV) and half-metallic edge states was realized in a PbC/MnSe heterostructure.

scholarly journals Evidence for one-dimensional chiral edge states in a magnetic Weyl semimetal Co3Sn2S2

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Sean Howard ◽  
Lin Jiao ◽  
Zhenyu Wang ◽  
Noam Morali ◽  
Rajib Batabyal ◽  
...  
Keyword(s):  
Practical Interest ◽  
Interlayer Coupling ◽  
Scanning Tunneling Spectroscopy ◽  
Scanning Tunneling ◽  
Edge States ◽  
New Paradigm ◽  
Linear Dispersion ◽  
Weyl Semimetal ◽  
Chern Insulators ◽  
Higher Temperature

AbstractThe physical realization of Chern insulators is of fundamental and practical interest, as they are predicted to host the quantum anomalous Hall (QAH) effect and topologically protected chiral edge states which can carry dissipationless current. Current realizations of the QAH state often require complex heterostructures and sub-Kelvin temperatures, making the discovery of intrinsic, high temperature QAH systems of significant interest. In this work we show that time-reversal symmetry breaking Weyl semimetals, being essentially stacks of Chern insulators with inter-layer coupling, may provide a new platform for the higher temperature realization of robust chiral edge states. We present combined scanning tunneling spectroscopy and theoretical investigations of the magnetic Weyl semimetal, Co3Sn2S2. Using modeling and numerical simulations we find that depending on the strength of the interlayer coupling, chiral edge states can be localized on partially exposed kagome planes on the surfaces of a Weyl semimetal. Correspondingly, our dI/dV maps on the kagome Co3Sn terraces show topological states confined to the edges which display linear dispersion. This work provides a new paradigm for realizing chiral edge modes and provides a pathway for the realization of higher temperature QAH effect in magnetic Weyl systems in the two-dimensional limit.

scholarly journals Novel Chern insulators with half-metallic edge states

2018 ◽  
Vol 10 (2) ◽  
pp. e467-e467 ◽  
Author(s):  
Yang Xue ◽  
Bao Zhao ◽  
Yan Zhu ◽  
Tong Zhou ◽  
Jiayong Zhang ◽  
...  
Keyword(s):  
Edge States ◽  
Half Metallic ◽  
Chern Insulators

scholarly journals Engineering of Chern insulators and circuits of topological edge states

2019 ◽  
Vol 99 (16) ◽  
Author(s):  
Emma L. Minarelli ◽  
Kim Pöyhönen ◽  
Gerwin A. R. van Dalum ◽  
Teemu Ojanen ◽  
Lars Fritz
Keyword(s):  
Edge States ◽  
Chern Insulators

scholarly journals Superior robustness of anomalous non-reciprocal topological edge states

Nature ◽  
2021 ◽  
Vol 598 (7880) ◽  
pp. 293-297
Author(s):  
Zhe Zhang ◽  
Pierre Delplace ◽  
Romain Fleury
Keyword(s):  
Energy Transport ◽  
Quantum Hall ◽  
Edge States ◽  
Small Perturbations ◽  
Transmission Modes ◽  
Hall Effects ◽  
Order Of Magnitude ◽  
Chern Insulators ◽  
Planar Geometries ◽  
Spin Hall Effects

AbstractRobustness against disorder and defects is a pivotal advantage of topological systems1, manifested by the absence of electronic backscattering in the quantum-Hall2 and spin-Hall effects3, and by unidirectional waveguiding in their classical analogues4,5. Two-dimensional (2D) topological insulators4–13, in particular, provide unprecedented opportunities in a variety of fields owing to their compact planar geometries, which are compatible with the fabrication technologies used in modern electronics and photonics. Among all 2D topological phases, Chern insulators14–25 are currently the most reliable designs owing to the genuine backscattering immunity of their non-reciprocal edge modes, brought via time-reversal symmetry breaking. Yet such resistance to fabrication tolerances is limited to fluctuations of the same order of magnitude as their bandgap, limiting their resilience to small perturbations only. Here we investigate the robustness problem in a system where edge transmission can survive disorder levels with strengths arbitrarily larger than the bandgap—an anomalous non-reciprocal topological network. We explore the general conditions needed to obtain such an unusual effect in systems made of unitary three-port non-reciprocal scatterers connected by phase links, and establish the superior robustness of anomalous edge transmission modes over Chern ones to phase-link disorder of arbitrarily large values. We confirm experimentally the exceptional resilience of the anomalous phase, and demonstrate its operation in various arbitrarily shaped disordered multi-port prototypes. Our results pave the way to efficient, arbitrary planar energy transport on 2D substrates for wave devices with full protection against large fabrication flaws or imperfections.

scholarly journals Floquet Chern insulators of light

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Li He ◽  
Zachariah Addison ◽  
Jicheng Jin ◽  
Eugene J. Mele ◽  
Steven G. Johnson ◽  
...  
Keyword(s):  
Eigenvalue Problem ◽  
Topological Invariant ◽  
Band Gaps ◽  
Optical Systems ◽  
Topological Phases ◽  
Edge States ◽  
Driven Systems ◽  
Nonlinear Photonic Crystals ◽  
Chern Insulators ◽  
Breaking Time

Abstract Achieving topologically-protected robust transport in optical systems has recently been of great interest. Most studied topological photonic structures can be understood by solving the eigenvalue problem of Maxwell’s equations for static linear systems. Here, we extend topological phases into dynamically driven systems and achieve a Floquet Chern insulator of light in nonlinear photonic crystals (PhCs). Specifically, we start by presenting the Floquet eigenvalue problem in driven two-dimensional PhCs. We then define topological invariant associated with Floquet bands, and show that topological band gaps with non-zero Chern number can be opened by breaking time-reversal symmetry through the driving field. Finally, we numerically demonstrate the existence of chiral edge states at the interfaces between a Floquet Chern insulator and normal insulators, where the transport is non-reciprocal and uni-directional. Our work paves the way to further exploring topological phases in driven optical systems and their optoelectronic applications.

scholarly journals TOPOLOGICAL FLAT BAND MODELS AND FRACTIONAL CHERN INSULATORS

2013 ◽  
Vol 27 (24) ◽  
pp. 1330017 ◽  
Author(s):  
EMIL J. BERGHOLTZ ◽  
ZHAO LIU
Keyword(s):  
Tight Binding ◽  
Cold Atom ◽  
Flat Band ◽  
Strongly Correlated ◽  
Edge States ◽  
Fractional Quantum Hall ◽  
Flat Bands ◽  
Topological Quantum ◽  
Chern Insulators ◽  
Topological Quantum Computation

Topological insulators and their intriguing edge states can be understood in a single-particle picture and can as such be exhaustively classified. Interactions significantly complicate this picture and can lead to entirely new insulating phases, with an altogether much richer and less explored phenomenology. Most saliently, lattice generalizations of fractional quantum Hall states, dubbed fractional Chern insulators, have recently been predicted to be stabilized by interactions within nearly dispersionless bands with nonzero Chern number, C. Contrary to their continuum analogues, these states do not require an external magnetic field and may potentially persist even at room temperature, which make these systems very attractive for possible applications such as topological quantum computation. This review recapitulates the basics of tight-binding models hosting nearly flat bands with nontrivial topology, C≠0, and summarizes the present understanding of interactions and strongly correlated phases within these bands. Emphasis is made on microscopic models, highlighting the analogy with continuum Landau level physics, as well as qualitatively new, lattice specific, aspects including Berry curvature fluctuations, competing instabilities as well as novel collective states of matter emerging in bands with |C|>1. Possible experimental realizations, including oxide interfaces and cold atom implementations as well as generalizations to flat bands characterized by other topological invariants are also discussed.

scholarly journals Epitaxial Growth of Quasi-One-Dimensional Bismuth-Halide Chains with Atomically Sharp Topological Non-Trivial Edge States

ACS Nano ◽  
2021 ◽  
Author(s):  
Jincheng Zhuang ◽  
Jin Li ◽  
Yundan Liu ◽  
Dan Mu ◽  
Ming Yang ◽  
...  
Keyword(s):  
Epitaxial Growth ◽  
Edge States ◽  
One Dimensional

scholarly journals Group Velocity Modulation and Light Field Focusing of the Edge States in Chirped Valley Graphene Plasmonic Metamaterials

Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1808
Author(s):  
Liqiang Zhuo ◽  
Huiru He ◽  
Ruimin Huang ◽  
Shaojian Su ◽  
Zhili Lin ◽  
...  
Keyword(s):  
Group Velocity ◽  
Light Field ◽  
Slow Light ◽  
Dielectric Materials ◽  
Degree Of Freedom ◽  
Geometrical Parameters ◽  
Edge States ◽  
Velocity Modulation ◽  
Plasmonic Metamaterials ◽  
On Chip

The valley degree of freedom, like the spin degree of freedom in spintronics, is regarded as a new information carrier, promoting the emerging valley photonics. Although there exist topologically protected valley edge states which are immune to optical backscattering caused by defects and sharp edges at the inverse valley Hall phase interfaces composed of ordinary optical dielectric materials, the dispersion and the frequency range of the edge states cannot be tuned once the geometrical parameters of the materials are determined. In this paper, we propose a chirped valley graphene plasmonic metamaterial waveguide composed of the valley graphene plasmonic metamaterials (VGPMs) with regularly varying chemical potentials while keeping the geometrical parameters constant. Due to the excellent tunability of graphene, the proposed waveguide supports group velocity modulation and zero group velocity of the edge states, where the light field of different frequencies focuses at different specific locations. The proposed structures may find significant applications in the fields of slow light, micro–nano-optics, topological plasmonics, and on-chip light manipulation.

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

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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