Anomalous Bulk-Surface Acoustic Decoupling in Topological Metamaterial Heterostructures

This proposal outlines an experimental framework to isolate and sustain extreme high-frequency Surface Acoustic Waves (SAW) on a 2D topological boundary layer without inducing phonon scattering into the supporting 3D bulk substrate. By bonding a topological insulator surface state (Bismuth-Antimony alloy, Bi1−xSbx) to a 3D phononic crystal exhibiting an absolute acoustic bandgap (micro-architected silicon), we hypothesize the creation of a "perfect decoupling limit." We define this limit using a dimensionless kinetic ratio, Γ→∞. When driven at critical resonance, the heterostructure is predicted to exhibit violent, sustained geometric phase-slippage at the topological boundary, while maintaining absolute elastodynamic zero-state in the bulk interior. This architecture offers unprecedented pathways for macroscopic mechanical isolation in aerospace and quantum computing substrates.