Magnetically tunable topological interface states for Lamb waves in one-dimensional magnetoelastic phononic crystal slabs

Topological interface states have attracted extensive research interest due to their unprecedented field confinement and enhancement at the interface between two one-dimensional phononic crystals with distinct topological characteristics. However, the realization of the contactless, nondestructive, and intelligent tunability of topological interface states, as the foundation for designing novel devices with unconventional functionalities, still remains a great challenge. Here, we introduce intelligent magnetoelastic materials to the topological system and realize magnetically tunable topological interface states for Lamb waves in one-dimensional phononic crystal slabs composed of alternating nonmagnetic and magnetoelastic layers. The properties of magnetoelastic layers can be tuned with noncontact, nondestruction, and intelligence by an external magnetic field. By changing the value of the external magnetic field applied on intercell and intracell magnetoelastic layers, the spatial variation of the properties of magnetoelastic layers is induced, resulting in an in situ topological phase transition. We demonstrate that topological interface states appear at the interface between two topologically different magnetoelastic phononic crystal slabs. Furthermore, based on the tunability of the external magnetic field, the existence of topological interface states can be switched and the frequency of topological interface states can be continuously tuned. In particular, the arbitrary positions of topological interface states can be dynamically achieved by varying the external magnetic field without altering the structure. Our tunable topological system can enable intelligent Lamb-wave devices with remarkable functionalities, which can lead to significant advances in intelligently controlled Lamb-wave switches, magnetically tunable frequency selectors, and magnetic control Lamb-wave communications.