Guiding Robust Valley-Dependent Edge States By Surface Acoustic Waves

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. In addition to a direct visualization of the valley-dependent modes excited from the corresponding chiral sources, the backscattering suppression of SAW valley-dependent edge modes 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. Published under license by AIP Publishing.