Experimental realization of on-chip topological nanoelectromechanical metamaterials

TL;DR

This paper reports the experimental creation of on-chip topological nanoelectromechanical metamaterials using silicon nitride nanomembranes, demonstrating robust edge states and potential for high-frequency acoustic signal processing.

Contribution

It presents the first experimental realization of topological phononic insulators at the nanoscale with high-frequency operation and demonstrated robustness to defects.

Findings

Edge states localized at the boundaries of the arrays

Dirac cone-like frequency dispersion observed

Waveguides show robustness to distortions

Abstract

Topological mechanical metamaterials translate condensed matter phenomena, like non-reciprocity and robustness to defects, into classical platforms. At small scales, topological nanoelectromechanical metamaterials (NEMM) can enable the realization of on-chip acoustic components, like unidirectional waveguides and compact delay-lines for mobile devices. Here, we report the experimental realization of NEMM phononic topological insulators, consisting of two-dimensional arrays of free-standing silicon nitride (SiN) nanomembranes that operate at high frequencies (10-20 MHz). We experimentally demonstrate the presence of edge states, by characterizing their localization and Dirac cone-like frequency dispersion. Our topological waveguides also exhibit robustness to waveguide distortions and pseudospin-dependent transport. The suggested devices open wide opportunities to develop functional acoustic systems for high-frequency signal processing applications.