Topological materials for full-vector elastic waves

Ying Wu; Jiuyang Lu; Xueqin Huang; Yating Yang; Li Luo; Linyun Yang; Feng Li; Weiyin Deng; Zhengyou Liu

doi:10.1093/nsr/nwac203

Topological materials for full-vector elastic waves

Natl Sci Rev. 2022 Sep 24;10(5):nwac203. doi: 10.1093/nsr/nwac203. eCollection 2023 May.

Authors

Ying Wu^{1

2}, Jiuyang Lu¹, Xueqin Huang¹, Yating Yang¹, Li Luo¹, Linyun Yang³, Feng Li⁴, Weiyin Deng¹, Zhengyou Liu^{5

6}

Affiliations

¹ School of Physics and Optoelectronics and State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou510640, China.
² Institute of Solid Mechanics, Midea Corporate Research Center, Midea Group, Foshan528311, China.
³ Department of Astronautic Science and Mechanics, Harbin Institute of Technology, Harbin150001, China.
⁴ Centre for Quantum Physics, Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement (MOE), School of Physics, Beijing Institute of Technology, Beijing100081, China.
⁵ Key Laboratory of Artificial Micro- and Nanostructures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan430072, China.
⁶ Institute for Advanced Studies, Wuhan University, Wuhan430072, China.

Abstract

Elastic wave manipulation is important in a wide variety of applications, including information processing in small elastic devices and noise control in large solid structures. The recent emergence of topological materials has opened new avenues for modulating elastic waves in solids. However, because of the full-vector feature and the complicated couplings of the longitudinal and transverse components of elastic waves, manipulating elastic waves is generally difficult compared with manipulating acoustic waves (scalar waves) and electromagnetic waves (vectorial waves but transverse only). To date, topological materials, including insulators and semimetals, have been used for acoustic and electromagnetic waves. Although topological materials with elastic waves have also been reported, the observed topological edge modes lie on the domain wall. A natural question arises: Is there an elastic metamaterial with topological edge modes on its own boundary? Here, we report a 3D metal-printed bilayer metamaterial that topologically insulates elastic waves. By introducing chiral interlayer couplings, the spin-orbit couplings for elastic waves are induced, which give rise to nontrivial topological properties. Helical edge states with vortex features were demonstrated on the boundary of the single topological phase. We further show a heterostructure of the metamaterial that exhibits tunable edge transport. Our findings could be used in devices based on elastic waves in solids.

Keywords: edge states; elastic waves; topological insulators.