THERMALLY TUNABLE TOPOLOGICAL PROPERTIES IN FERROELECTRIC PHONONIC CRYSTALS

The elastic analogies of Topological concepts, including Hall effect, quantum spin Hall effect, topological isolators and so on, are intensively studied in these years. Based on the knowledges of topological properties, a lot of novel wave propagation phenomena, such as one-way edge mode and topologically protected interface/edge modes that can pass through sharp corners without diffusion and be robust to the defects in the structure, have been numerically achieved and experimentally proved. Most of the present studies are focused on passive materials, which means once the devices are designed and manufactured, they can only work in fixed and narrow frequency ranges. With the fast development of the artificial intelligence, devices that can be tuned at will are highly desired. Therefore, the active phononic crystals made of ferroelectric materials will be designed and analyzed in this paper. The influences of structural parameters and the temperature on the topological properties will be studied. Finally, based on the knowledges of the distribution of the topological state (determined by topological invariants) as functions of the structural parameters and the temperature, the thermally tunable wave-guidings with zigzag path or controllable path will be designed and numerically studied. These active phononic crystals possessing thermally tunable topological properties have wide applications in wave-guiding engineering, energy harvester, signal processing, vibration/noise control, etc.