Realization of Weyl elastic metamaterials with spin skyrmions

TL;DR

This paper reports the first realization of 3D printed Weyl elastic metamaterials with stable spin skyrmion textures, enabling robust manipulation of elastic waves in three dimensions through topologically protected states.

Contribution

It demonstrates the experimental creation of an all-metallic Weyl elastic metamaterial with observable topological features and spin textures, overcoming previous fabrication challenges.

Findings

Successful fabrication of low-loss 3D printed Weyl elastic metamaterial

Observation of Weyl points and Fermi arcs via laser vibrometry

Detection of spin skyrmion textures in elastic wave excitations

Abstract

Topological elastic metamaterials provide a topologically robust way to manipulate the phononic energy and information beyond the conventional approaches. Among various topological elastic metamaterials, Weyl elastic metamaterials stand out, as they are unique to three dimensions and exhibit numerous intriguing phenomena and potential applications. To date, however, the realization of Weyl elastic metamaterials remains elusive, primarily due to the full-vectoral nature of elastic waves and the complicated couplings between polarizations, leading to complicated and tangled three-dimensional (3D) bandstructures that unfavorable for experimental demonstration. Here, we overcome the challenge and realize an ideal, 3D printed, all-metallic Weyl elastic metamaterial with low dissipation losses. Notably, the elastic spin of the excitations around the Weyl points exhibits skyrmion textures, a topologically stable structure in real space. Utilizing 3D laser vibrometry, we reveal the projection of the Weyl points, the Fermi arcs and the unique spin characteristics of the topological surface states. Our work extends the Weyl metamaterials to elastic waves and paves a topological way to robust manipulation of elastic waves in 3D space.