Guiding Robust Valley-dependent Edge States by Surface Acoustic Waves

TL;DR

This paper demonstrates surface acoustic wave waveguides that utilize valley pseudospins in phononic crystals, enabling robust, backscattering-immune edge state transport for advanced phononic circuits.

Contribution

It introduces SAW waveguides that harness valley pseudospins in 2D phononic crystals, showing robust edge state transport and backscattering suppression.

Findings

Visualization of valley-dependent states from chiral sources

Backscattering suppression in curved interfaces

Robust elastic wave energy transport

Abstract

Recently, the concept of valley pseudospin, labeling quantum states of energy extrema in momentum space, has attracted enormous attention because of its potential as a new type of information carrier. Here, we present surface acoustic wave (SAW) waveguides, which utilize and transport valley pseudospins in two-dimensional SAW phononic crystals (PnCs). In addition to a direct visualization of the valley-dependent states excited from the corresponding chiral sources, the backscattering suppression of SAW valley-dependent edge states transport is observed in sharply curved interfaces. By means of band structure engineering, elastic wave energy in the SAW waveguides can be transported with remarkable robustness, which is very promising for new generations of integrated solid-state phononic circuits with great versatility.