Nanomechanical topological insulators with an auxiliary orbital degree of freedom

Abstract

Discrete degrees of freedom, such as spin and orbital, can provide intriguing strategies to manipulate electrons, photons, and phonons. With a spin degree of freedom, topological insulators have stimulated intense interests in condensed-matter physics, optics, acoustics, and mechanics. However, orbital as another fundamental attribute in crystals has seldom been investigated in topological insulators. Here, we invent a new type of topological insulators with an auxiliary orbital degree of freedom on a nanomechanical platform. We experimentally realized nanomechanical topological insulators where the orbital can arbitrarily be manipulated by the crystal. Harnessing this unique feature, we demonstrated adiabatic transition between distinct topological edge states, which is a crucial functionality for complicated systems that involve distinct topological edge channels. Beyond the one-dimensional edge states, we further constructed zero-dimensional Dirac-vortex states. Our results have unveiled unprecedented strategies to manipulate topological phase transitions and to study topological phases of matter on an integrated platform.

arXiv commentNat. Nanotechnol. (2021)

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• Monopole topological resonators
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• Geometric control of topological dynamics in a singing saw
• A mono-atomic orbital-based 1D topological crystalline insulator
• Fluctuation instabilities via internal resonance in a multimode membrane as a mechanism for frequency combs
• Deployable Nanoelectromechanical Bound States in the Continuum Enabled by GHz Lamb Wave Phononic Crystals on LiNbO3 Thin Films