Singular Topological Edge States in Locally Resonant Metamaterials

Fuente: arXiv
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Autores principales: Jang, Yeongtae, Kim, Seokwoo, Kim, Eunho, Rho, Junsuk
Formato: Preprint
Publicado: 2024
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author Jang, Yeongtae
Kim, Seokwoo
Kim, Eunho
Rho, Junsuk
author_facet Jang, Yeongtae
Kim, Seokwoo
Kim, Eunho
Rho, Junsuk
contents Band topology has emerged as a novel tool for material design across various domains, including photonic and phononic systems, and metamaterials. A prominent model for band topology is the Su-Schrieffer-Heeger (SSH) chain, which reveals topological in-gap states within Bragg-type gaps (BG) formed by periodic modification. Apart from classical BGs, another mechanism for bandgap formation in metamaterials involves strong coupling between local resonances and propagating waves, resulting in a local resonance-induced bandgap (LRG). Previous studies have shown the challenge of topological edge state emergence within the LRG. Here, we reveal that topological edge states can emerge within an LRG by achieving both topological phase and bandgap transitions simultaneously. We describe this using a model of inversion-symmetric extended SSH chains for locally resonant metamaterials. Notably, this topological state can lead to highly localized modes, comparable to a subwavelength unit cell, when it emerges within the LRG. We experimentally demonstrate distinct differences in topologically protected modes -- highlighted by wave localization -- between the BG and the LRG using locally resonant granule-based metamaterials. Our findings suggest the scope of topological metamaterials may be extended via their bandgap nature.
format Preprint
id arxiv_https___arxiv_org_abs_2405_13631
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Singular Topological Edge States in Locally Resonant Metamaterials
Jang, Yeongtae
Kim, Seokwoo
Kim, Eunho
Rho, Junsuk
Other Condensed Matter
Applied Physics
Band topology has emerged as a novel tool for material design across various domains, including photonic and phononic systems, and metamaterials. A prominent model for band topology is the Su-Schrieffer-Heeger (SSH) chain, which reveals topological in-gap states within Bragg-type gaps (BG) formed by periodic modification. Apart from classical BGs, another mechanism for bandgap formation in metamaterials involves strong coupling between local resonances and propagating waves, resulting in a local resonance-induced bandgap (LRG). Previous studies have shown the challenge of topological edge state emergence within the LRG. Here, we reveal that topological edge states can emerge within an LRG by achieving both topological phase and bandgap transitions simultaneously. We describe this using a model of inversion-symmetric extended SSH chains for locally resonant metamaterials. Notably, this topological state can lead to highly localized modes, comparable to a subwavelength unit cell, when it emerges within the LRG. We experimentally demonstrate distinct differences in topologically protected modes -- highlighted by wave localization -- between the BG and the LRG using locally resonant granule-based metamaterials. Our findings suggest the scope of topological metamaterials may be extended via their bandgap nature.
title Singular Topological Edge States in Locally Resonant Metamaterials
topic Other Condensed Matter
Applied Physics
url https://arxiv.org/abs/2405.13631