Canonical scattering problems in topological metamaterials : Valley-Hall modes through bends

Résumé : Topological insulators are a class of material, oftentimes constructed from an underlying periodic structure, which exhibit exotic wave properties. In such materials, waves are unable to propagate in the bulk but can travel at their surface with exceptional robustness and efficiency. The most striking example is the quantum Hall effect, where electrons propagate at the surface with a perfect transmission across defects due to their spin properties. In classical systems, such as acoustical or mechanical metamaterials, one does not have access to the spin property of quantum mechanics. However, it is possible to construct pseudo-spins which partially protects the wave propagation against defects. In this talk, we will focus on a particular realisation of such pseudo-spin : the valley Hall effect in a system inspired from acoustical graphene. We will study quantitatively the topological protection and the transport properties of the valley Hall modes through canonical obstacles, namely sharp turns in a graphene ribbon. 

Le 4 juillet 2023 de 11h00 à 12h00 / Amphithéâtre François Canac, LMA

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