Trapped state at a dislocation in a weak magnetomechanical topological insulator

Abstract

Topological insulators (TIs) are characterized by an insulating bulk and symmetry protected bound state on their boundaries. A "strong" topological insulator is characterized by robust conducting states on \emph{all} boundaries protected by certain internal symmetries. A "weak" topological insulator (WTI) however, requires lattice translation symmetry, making it more sensitive to disorder. However, this sensitivity gives rise to interesting characteristics such as anisotropic edge modes, quantized charge polarization, and bound states appearing at dislocation defects. Despite hosting interesting features, the sensitivity of WTIs to disorder poses an experimental confirmation challenge. Here we realize a 2D magneto-mechanical metamaterial and demonstrate experimentally the unique features of a WTI. Specifically, we show that the 2D WTI is anisotropic and hosts edge modes only on certain edges, as well as hosting a bound state at a dislocation defect. We construct the 2D WTI from stacked 1D SSH chains for which we show experimentally the different gapped phases of the 1D model.

arXiv comment15.9 + 9.9 pages. 4+2 figures

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• Dislocation as a bulk probe of higher-order topological insulators
• Bound states at partial dislocation defects in multipole higher-order topological insulators
• Anomalous and normal dislocation modes in Floquet topological insulators
• Non-Hermitian dislocation modes: Stability and melting across exceptional points
• Observing 0D subwavelength-localized modes at ~100 THz protected by weak topology
• Dynamical Detection of Topological Spectral Density
• Cataloging topological phases of $N$-stacked Su-Schrieffer-Heeger chains by a systematic breaking of symmetries
• Spontaneously-Induced Dirac Boundary State and Digitization in a Nonlinear Resonator Chain
• Emergent metallicity at the grain boundaries of higher-order topological insulators
• Vavilov-Cherenkov radiation for parallel motion in three-dimensional topological insulators
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• Dispersive nodal fermions along grain boundaries in Floquet topological crystals
• Fragile dislocation modes in obstructed atomic topological phases
• Spectroscopic footprints of quantum friction in nonreciprocal and chiral media
• Topological Dislocation Response in Elementary Semiconductors