Valley Vortex States in Sonic Crystals

TL;DR

This paper explores valley vortex states in sonic crystals, revealing their vortex nature and proposing a sound spin Hall effect, which could enable advanced sound manipulation and vortex control in acoustics.

Contribution

It introduces the acoustic valley vortex states, demonstrates their vortex nature, and proposes a mimicked spin Hall effect for sound in sonic crystals.

Findings

Discovery of vortex nature in acoustic valley states

Proposal of a mimicked spin Hall effect of sound

Potential for vortex-based sound manipulation

Abstract

Valleytronics is quickly emerging as an exciting field in fundamental and applied research. In this Letter, we study the acoustic version of valley states in sonic crystals and reveal a vortex nature of such states. Besides the selection rules established for exciting valley polarized states, a mimicked spin Hall effect of sound is proposed further. The extraordinary chirality of valley vortex states, detectable in experiments, may open new possibility in sound manipulations. This is appealing to scalar acoustics that lacks spin degree of freedom inherently. Besides, the valley selection enables a handy way to create vortex matter in acoustics, in which the vortex chirality can be controlled flexibly. Potential applications can be anticipated with the exotic interaction of acoustic vortices with matter, such as to trigger the rotation of the trapped microparticles without contact.