Coupled Edge States and Pseudospin‐Switching Transport of Elastic Waves in Topological Phononic Heterostructure

Elastic topological insulators (ETIs) with topologically protected edge states featuring one‐way, robustness and backscattering‐immunity possess extraordinary abilities to steer and manipulate elastic wave. In this article, we investigate the finite‐size effect of the ETI and reveal the pseudospin‐switching transport of the coupled topological edge states for in‐plane bulk elastic wave. By designing a solid topological phononic crystals (PnC) with honeycomb lattice, the pseudospin topological phase transition of elastic wave is realized, and then the coupled topological edge states are realized based on the construction of the topological heterostructure. By setting different layer numbers of the middle domain in topological heterostructure, the finite‐size effects of the edge states are systematically investigated, and the pseudospin flipping effect of the coupled edge state is revealed. Finally, based on the finite‐size effect of the topological PnCs, the robustness and pseudospin‐switching transport of the coupled edge states are further demonstrated. The proposed results provide new approaches and thoughts to improve the development of elastic topological devices in the future.