Valley edge states and chiral selective transport in reconfigurable phononic crystals

Valley topological edge state has been extended from condensed matter physics to acoustics and rapidly developed, in which one-way propagation in valley topological phononic crystal is achieved breaking the spatial reversal symmetry. Here, we present a 2D hexagonal lattice phononic crystal with the reconfigurable scatters composed of three rectangle rods. By rotating its three-legged rods, two distinct valley edge states can be realised and the valley Hall topological transition phase also is triggered. We numerically simulate the projected band structures of the supercells including zigzag and armchair interface and verify the existence of valley edge states. We demonstrate the acoustic topological transport in the straight interface and sharply curved path. Then, in an across-interface, acoustic splitting and emerging are also observed. Furthermore, we design the complicated interfaces constructed by phononic crystals with distinct valley Hall topological phase. We verify the chiral selective transports in the oriented interface if the excited point source positioned at different interfaces. The chiral selective valley topological propagation of acoustic wave provides many potential applications in designing acoustic switch, splitter and acoustic waveguide. Graphical abstract