Abnormal edge states induced by sliding interfaces in valley topological phononic crystal plates

Abstract The concept of topology has attracted tremendous attention in classical wave systems in the past decade. The robust and chiral properties of topological system provide fantastic toolkits to control the wave behaviors. In this work, an alternative method has been proposed to construct edge states in phononic crystal (PnC) plates without requiring topological phase transition. These edge states are realized by shifting part of the valley topological PnC plate, and are called as abnormal edge states. These abnormal edge states are demonstrated to be robust against sample defects such as cavity, disorder and sharp bend. By using these abnormal edge states, frequency dependent wave routes also have been built up, in which the elastic waves can be guided to different ports at different frequencies. These results enrich the design of topological PnC devices.