Electrically Tunable Elastic Topological Insulators Using Atomically Thin Two-Dimensional Materials Pinned on Patterned Substrates

At present, functionalities, miniaturization, and tunability are useful directions in the development of practical device applications for topological photonics and phononics. Atomically thin two-dimensional (2D) materials not only have excellent mechanical properties, but also have outstanding electrical, optical, and magnetic properties, making them great candidates for tunable microdevices via electrostatic forces, magnetoacoustic, or photoacoustic coupling, etc. In this paper, we propose an elastic topological insulator based on atomically thin 2D materials pinned on honeycomb-patterned substrates. Thanks to acoustic impedance mismatch between the suspended 2D materials and the rigid substrates, both topological edge states and corner states of elastic waves inside the 2D materials can be achieved, accompanied by a display of functional components, e.g., arbitrary waveguides, splitters, resonators. Significantly, all these components for elastic waves are frequency tunable, due to the electromechanical sensitivity of the 2D material. For example, a two-port high -Q bandpass filter is estimated to achieve 7.26% operating frequency shifting by applying only 5 V of gate voltage. These kinds of elastic topological materials and corresponding devices can strongly promote the development of 2D-material-based nanoelectromechanical systems and might have immediate applications in modern wireless communication technology at radio or microwave frequencies.

Automated summary

The paper introduces an elastic topological insulator based on atomically thin 2D materials, which can achieve topological edge states and corner states of elastic waves, accompanied by functional components. These components, such as waveguides, splitters, and resonators for elastic waves, are frequency tunable due to the electromechanical sensitivity of 2D materials.