Elastic valley Hall phases in bilayer phononic crystal.

In this Letter, a bilayer elastic C6v structure is proposed and used to precisely manipulate two topological nontrivial valley pseudo-spin states. According to the theoretical simulation results, the two elastic pseudo-spin states have opposite valley polarizations along propagation directions. Owing to the interlayer polarization and mixing effects of the elastic valley pseudo-spin states in the bilayer elastic C6v structure, the transport and prohibition of elastic valley pseudo-spin states and even the tunneling between layers are flexibly manipulated. The transmission efficiency of elastic valley pseudo-spin states across layers reaches 93%, which has also been confirmed in experiments by the laser ultrasonic method. The in-depth exploration of valley pseudo-spin states with layer indices further expands and enriches the research of valley pseudo-spin states in the elastic environment and lays the foundation for the further design of elastic topological devices. [ABSTRACT FROM AUTHOR]