Tunable Acoustic Valley-Hall Edge States in Reconfigurable Phononic Elastic Waveguides

Abstract

This study investigates the occurrence of acoustic topological edge states in a 2D phononic elastic waveguide due to a phenomenon that is the acoustic analogue of the quantum valley Hall effect. We show that a topological transition takes place between two lattices having broken space inversion symmetry due to the application of a tunable strain field. This condition leads to the formation of gapless edge states at the domain walls, as further illustrated by the analysis of the bulk-edge correspondence and of the associated topological invariants. Although time reversal symmetry is still intact in these systems, the edge states are topologically protected when inter-valley mixing is either weak or negligible. Interestingly, topological edge states can also be triggered at the boundary of a single domain if boundary conditions are properly selected. We also show that the static modulation of the strain field allows tuning the response of the material between the different supported edge states.

9 pages, 13 figures

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• The electronic properties of graphene
• Topological Acoustics
• Analogs of quantum Hall effect edge states in photonic crystals
• Observation of phononic helical edge states in a mechanical 'topological insulator'
• Observation of topological valley transport of sound in sonic crystals
• Topological confinement in bilayer graphene
• Valley Vortex States in Sonic Crystals
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• Edge waves in plates with resonators: An elastic analogue of the quantum valley Hall effect
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Cited by in corpus (8)

• Double Dirac Cones and Topologically Non-Trivial Phonons for Continuous, Square Symmetric (C${}_{4v}$ and C${}_{2v}$) Unit Cells
• Design of GaAs-based valley phononic crystals with multiple complete phononic bandgaps at ultra-high frequency
• Topological transition in spiral elastic valley metamaterials
• Structure-Composition Correspondence in Crystalline Metamaterials for Acoustic Valley-Hall Effect and Unidirectional Sound Guiding
• Corner states in second-order mechanical topological insulator
• Design of Large Sequential Conformational Change in Mechanical Networks
• Low-frequency tunable topological interface states in soft phononic crystal cylinders
• Topological defect states in elastic phononic plates