Valley transport in sonic crystals

Like the spin in spintronics, the valley index in solid-state materials can be viewed as a new carrier of information, which is useful for designing modern electronic devices. Recently, we have applied the concept of valleytronics to sonic crystals, revealed the vortex nature of valley states, and established valley-selection rules. Interestingly, the acoustic valley states can be stimulated directly by external sound, and detected through the field distributions inside and outside the crystal. The vortex chirality-locked valley transport enables a novel manipulation of sound. Considering the interaction between sound and matter, other fancy applications can also be anticipated for the valley vortex states, such as rotating micro-particles. In addition, we find that there exist two kinds of topologically distinct acoustic valley Hall phases, and an interface separating them can host topologically-protected edge states, associated with many exotic transport properties (such as valley selective excitations and antireflection in bent corners).