Thermally controlled topological states for elastic waves

Abstract

Developing a tunable phononic crystal (PC) based on relatively simple technology is challenging. Herein, we report a thermally controlled two-dimensional PC which consists of a honeycomb array of thermosensitive perovskite ferroelectric scatterers. The inversion symmetry of the PC is broken, and the topological properties of the band structure are readily tuned by heating the scatterers in a well-controlled manner to form a temperature gradient in the unit cell. Numerical simulation is used to demonstrate the one-way propagation of the edge state along the interface between two PCs with different topological properties and robustness of the edge states against defects. The propagation of the interfacial wave can be tuned extensively by varying the temperature in a few unit cells of the honeycomb lattice array. The present study could be potentially significant in designing tunable, efficient, and multifunctional acoustic devices.