Topological triply degenerate point with double Fermi arcs

Unconventional chiral particles have recently been predicted to appear in certain three-dimensional crystal structures containing three- or more-fold linear band degeneracy points (BDPs)1,2,3,4. These BDPs carry topological charges, but are distinct from the standard twofold Weyl points or fourfold...

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Main Authors: Yang, Yihao, Sun, Hong-Xiang, Xia, Jian-Ping, Xue, Haoran, Gao, Zhen, Ge, Yong, Jia, Ding, Yuan, Shou-Qi, Chong, Yidong, Zhang, Baile
Other Authors: School of Physical and Mathematical Sciences
Format: Article
Language:English
Published: 2020
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Online Access:https://hdl.handle.net/10356/138230
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Institution: Nanyang Technological University
Language: English
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spelling sg-ntu-dr.10356-1382302023-02-28T20:04:24Z Topological triply degenerate point with double Fermi arcs Yang, Yihao Sun, Hong-Xiang Xia, Jian-Ping Xue, Haoran Gao, Zhen Ge, Yong Jia, Ding Yuan, Shou-Qi Chong, Yidong Zhang, Baile School of Physical and Mathematical Sciences Centre for Disruptive Photonic Technologies The Photonics Institute Science::Physics Acoustics Topological Matter Unconventional chiral particles have recently been predicted to appear in certain three-dimensional crystal structures containing three- or more-fold linear band degeneracy points (BDPs)1,2,3,4. These BDPs carry topological charges, but are distinct from the standard twofold Weyl points or fourfold Dirac points, and cannot be described in terms of an emergent relativistic field theory1. Here we report on the experimental observation of a topological threefold BDP in a three-dimensional phononic crystal. Using direct acoustic field mapping, we demonstrate the existence of the threefold BDP in the bulk band structure, as well as doubled Fermi arcs of surface states consistent with a topological charge of 2. Another novel BDP, similar to a Dirac point but carrying non-zero topological charge, is connected to the threefold BDP via the doubled Fermi arcs. The Fermi arcs form double helicoids spanning a broad frequency range (relative bandwidth >25%). We show that the non-contractibility of these arcs gives rise to the phenomenon of topologically protected negative refraction of surface states on all surfaces of the sample. Our work paves the way to using these unconventional particles for exploring new emergent physical phenomena, and may find applications in symmetry-stabilized three-dimensional zero-index metamaterials. 2020-04-29T06:18:15Z 2020-04-29T06:18:15Z 2019 Journal Article Yang, Y., Sun, H.-X., Xia, J.-P., Xue, H., Gao, Z., Ge, Y., . . . Zhang, B. (2019). Topological triply degenerate point with double Fermi arcs. Nature Physics, 15(7), 645-649. doi:10.1038/s41567-019-0502-z 1745-2473 https://hdl.handle.net/10356/138230 10.1038/s41567-019-0502-z 2-s2.0-85064750196 7 15 645 649 en Nature Physics 10.21979/N9/4G3YST © 2019 The Author(s), under exclusive licence to Springer Nature Limited. All rights reserved. This paper was published in Nature Physics and is made available with permission of The Author(s), under exclusive licence to Springer Nature Limited. application/pdf
institution Nanyang Technological University
building NTU Library
continent Asia
country Singapore
Singapore
content_provider NTU Library
collection DR-NTU
language English
topic Science::Physics
Acoustics
Topological Matter
spellingShingle Science::Physics
Acoustics
Topological Matter
Yang, Yihao
Sun, Hong-Xiang
Xia, Jian-Ping
Xue, Haoran
Gao, Zhen
Ge, Yong
Jia, Ding
Yuan, Shou-Qi
Chong, Yidong
Zhang, Baile
Topological triply degenerate point with double Fermi arcs
description Unconventional chiral particles have recently been predicted to appear in certain three-dimensional crystal structures containing three- or more-fold linear band degeneracy points (BDPs)1,2,3,4. These BDPs carry topological charges, but are distinct from the standard twofold Weyl points or fourfold Dirac points, and cannot be described in terms of an emergent relativistic field theory1. Here we report on the experimental observation of a topological threefold BDP in a three-dimensional phononic crystal. Using direct acoustic field mapping, we demonstrate the existence of the threefold BDP in the bulk band structure, as well as doubled Fermi arcs of surface states consistent with a topological charge of 2. Another novel BDP, similar to a Dirac point but carrying non-zero topological charge, is connected to the threefold BDP via the doubled Fermi arcs. The Fermi arcs form double helicoids spanning a broad frequency range (relative bandwidth >25%). We show that the non-contractibility of these arcs gives rise to the phenomenon of topologically protected negative refraction of surface states on all surfaces of the sample. Our work paves the way to using these unconventional particles for exploring new emergent physical phenomena, and may find applications in symmetry-stabilized three-dimensional zero-index metamaterials.
author2 School of Physical and Mathematical Sciences
author_facet School of Physical and Mathematical Sciences
Yang, Yihao
Sun, Hong-Xiang
Xia, Jian-Ping
Xue, Haoran
Gao, Zhen
Ge, Yong
Jia, Ding
Yuan, Shou-Qi
Chong, Yidong
Zhang, Baile
format Article
author Yang, Yihao
Sun, Hong-Xiang
Xia, Jian-Ping
Xue, Haoran
Gao, Zhen
Ge, Yong
Jia, Ding
Yuan, Shou-Qi
Chong, Yidong
Zhang, Baile
author_sort Yang, Yihao
title Topological triply degenerate point with double Fermi arcs
title_short Topological triply degenerate point with double Fermi arcs
title_full Topological triply degenerate point with double Fermi arcs
title_fullStr Topological triply degenerate point with double Fermi arcs
title_full_unstemmed Topological triply degenerate point with double Fermi arcs
title_sort topological triply degenerate point with double fermi arcs
publishDate 2020
url https://hdl.handle.net/10356/138230
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