Elastic valley Hall phases in bilayer phononic crystal

In this Letter, a bilayer elastic C-6v 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 C-6v 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.

Automated summary

In this Letter, a bilayer elastic C-6v structure is proposed and used to manipulate two topological nontrivial valley pseudo-spin states. The transmission and prohibition of the elastic valley pseudo-spin states, as well as the tunneling between layers, can be flexibly controlled due to the interlayer polarization and mixing effects in the structure. The experimental results confirm the high transmission efficiency of elastic valley pseudo-spin states across layers, reaching 93%. This research expands and enriches the understanding of valley pseudo-spin states in the elastic environment and lays the foundation for the design of elastic topological devices.