Observation of dislocation-induced topological modes in a three-dimensional acoustic topological insulator

TL;DR

This study experimentally demonstrates dislocation-induced topological helical modes in a 3D acoustic topological insulator, revealing potential for robust waveguides and new physical phenomena in classical topological materials.

Contribution

First direct observation of dislocation-induced helical modes in a 3D acoustic topological insulator, combining experimental, numerical, and theoretical approaches.

Findings

Dislocation-induced helical modes observed via spin-resolved field mapping.

Modes verified by tight-binding and finite-element calculations.

Helical channels act as robust waveguides in 3D media.

Abstract

The interplay between real-space topological lattice defects and the reciprocal-space topology of energy bands can give rise to novel phenomena, such as one-dimensional topological modes bound to screw dislocations in three-dimensional topological insulators. We obtain direct experimental observations of dislocation-induced helical modes in an acoustic analog of a weak three-dimensional topological insulator. The spatial distribution of the helical modes is found through spin-resolved field mapping, and verified numerically by tight-binding and finite-element calculations. These one-dimensional helical channels can serve as robust waveguides in three-dimensional media. Our experiment paves the way to studying novel physical modes and functionalities enabled by topological lattice defects in three-dimensional classical topological materials.