Reconfigurable localized effects in non-Hermitian phononic plate

Abstract

Skin effect is one of the intriguing phenomena exhibited by non-Hermitian wave systems. It reflects the localization of the modes at the boundaries of the structure. We demonstrated the skin effect for elastic waves propagating in a non-Hermitian phononic plate containing piezoelectric components in their unit cells. The latter behave as sensors and actuators by using the direct and inverse piezoelectric effects. The demonstration is based on the calculation of the complex non-reciprocal dispersion curves and their analysis for any direction of the wavevector in the two-dimensional space. Therefore, localization phenomena at different boundaries and corners of a finite square structure are presented. Furthermore, by applying different levels of non-Hermiticity in different parts of a square structure, it is shown that the localized features can appear at different positions and with various shapes. These localized phenomena can be reconfigured by acting on the non-Hermiticity parameters. Our results provided a feedback control strategy to introduce the non-Hermitian skin effect in two-dimensional elastic systems for potential applications, such as vibration control, energy harvesting, and sensing.