Measuring Band Structures in Acoustic Metamaterials Via Multiplexed Microphones

Twisted van der Waals heterostructures have emerged as tunable systems for studying correlated electrons. However, the process of exploring this vast phase space offor quantum materials is laborious and expensive. Acoustic metamaterials can be used to mimic the behaviors of these quantum materials, serving as cheap and rapid prototypes for vdW heterostructures. Twisted bilayer graphene is one such system that has already been successfully translated to an acoustic metamaterial, made up of air cavities in a steel matrix [1]. As acoustic metamaterials become larger and more complex to mimic, with smaller twist angles and larger moire unit cells, it is useful to be able to measure multiple lattice sites simultaneously in order to analyze the band structure of the quantum material analog. We have developed a multiplexed microphone circuit that greatly increases the efficiency of band structure measurements, and we have applied it to the acoustic metamaterial analog of graphene.