Topologically protected elastic waves in phononic metamaterials

• DOI: 10.1038/ncomms9682
• Publication Date: 2015-11-04T12:42:42Z
• Authors: S. Hossein Mousavi; Alexander B. Khan...; Zheng Wang
• Keywords: Topological insulator

Topological states of quantum matter exhibit unique disorder-immune surface protected by underlying nontrivial topological invariants the bulk. Such immunity from backscattering makes or edge ideal carriers for both classical and information. So far, matters have been explored only in realms electronics photonics, with limited range bulk properties largely immutable materials. These constraints thus impose severe performance trade-offs experimentally realizable topologically ordered states. In contrast, phononic metamaterials not provide access to a much wider material properties, but also allow temporal modulation non-adiabatic regime. Here, first-principles we demonstrate numerically first metamaterial an elastic-wave analogue spin Hall effect. A dual-scale crystal slab is used support two effective spins phonon over broad bandwidth, strong spin-orbit coupling realized breaking spatial mirror symmetry. By preserving polarization external load symmetry, are shown be robust against scattering discrete defects as well disorders continuum. Our system opens up possibility realizing materials phonons static time-dependent regimes.