Flat Bands and Moiré Potentials in Acoustic Twisted Bilayer Kagome*

The discovery of vdW heterostructures has opened a vast parameter space of materials and twist geometries too large for direct exploration. Acoustic metamaterials offer a solution to efficiently prototype their quantum counterparts. For example, twisted bilayer graphene has already been translated into the field of acoustics [1]. Here we simulate the acoustic metamaterial analog of a twisted bilayer kagome lattice composed of interconnected air cavities, separated by a thin interlayer membrane. Using COMSOL Multiphysics, we accurately mimic the flattening of the Dirac cone expected from a tight-binding approach, as well as the reorganization of the single-layer kagome flat band modes to form a larger kagome lattice on the Moiré length scale. Additionally, the tunable density and thickness of the interlayer membrane allow us to increase the magic angle, resulting in smaller, more computationally-tractable supercells that permit the exploration of physics beyond the first magic angle.

[1] S Minhal Gardezi et al, 2D Materials 8, 031002 (2021)