Bulk elastic waves with unidirectional backscattering-immune topological states in a time-dependent superlattice

N. Swinteck (1) , S. Matsuo (1) , K. Runge (1) , Jerome O. Vasseur (2) , P. Lucas (1) , P. Deymier (1)

1 Department of Materials Science and Engineering
2 ACOUSTIQUE - IEMN - Acoustique - IEMN

Recent progress in electronic and electromagnetic topological insulators has led to the demonstration of one way propagation of electron and photon edge states and the possibility of immunity to backscattering by edge defects. Unfortunately, such topologically protected propagation of waves in the bulk of a material has not been observed. We show, in the case of sound/elastic waves, that bulk waves with unidirectional backscattering-immune topological states can be observed in a time-dependent elastic superlattice. The superlattice is realized via spatial and temporal modulation of the stiffness of an elastic material. Bulk elastic waves in this superlattice are supported by a manifold in momentum space with the topology of a single twist Möbius strip. Our results demonstrate the possibility of attaining one way transport and immunity to scattering of bulk elastic waves.

Mots clés: Geometric topology; Telecommunications engineering; Bloch wave; String theory; Topological insulator; Wave mechanics; Crystal structure; Superlattices; Elastic waves; Electronic band structure

Domaines: Acoustique [physics.class-ph]

N. Swinteck, S. Matsuo, K. Runge, Jerome O. Vasseur, P. Lucas, et al.. Bulk elastic waves with unidirectional backscattering-immune topological states in a time-dependent superlattice. Journal of Applied Physics, 2015, 118 (6), pp.063103. ⟨10.1063/1.4928619⟩. ⟨hal-03304962⟩