Trapped State at a Dislocation in a Weak Magnetomechanical Topological Insulator

Observation of Dislocation-Induced Topological Modes in a Three-Dimensional Acoustic Topological Insulator

“…Our results, together with other recent related experimental efforts [18,[49][50][51], coincide with growing interest in the possibilities of combining band topology with lattice defects [17,[28][29][30][31]. One promising direction for future research is to extend the current design beyond the tightbinding regime.…”

“…Some signatures of these modes have been found in real materials through conductivity measurements [26] and local density of states measurements [27]. Classical wave systems such as photonic crystals and acoustic crystals have been used to demonstrate localized modes bound to dislocations in 2D photonic Chern insulators [28] and weak 2D magnetomechanical TIs [29], disclination waveguiding in 2D valley photonic crystals [17], and fractional mode density at lattice defects in 2D topological crystalline insulators [30,31]. However, the topological helical modes induced by a screw dislocation in a 3D TI [5] have not previously been realized.…”

Progress in Topological Mechanics

“…Topological lattice defects [27] have been extensively studied in electronic systems [138][139][140] and classical systems [141][142][143][144][145][146][147][148] over the past decade. The classification of topological lattice defects depends on the holonomy along a closed path around the defect core [25,149].…”

“…The dislocations and disclinations are defined as a gauge flux for translational symmetry and rotational symmetry, respectively [28]. Dislocations and disclinations are mainly investigated on honeycomb lattices and square lattices [149], and it has been demonstrated that they can serve as a bulk probe to detect the topological nature which exhibits topological states [139][140][141][142][143][146][147][148][154][155][156] and/or fractional charges [144,145,157,158] in TCIs protected by crystal symmetries. More recently, topological defect states have been proposed in elastic materials [87,[159][160][161], and then we will discuss the related papers.…”

Observation of dislocation-induced topological modes in a three-dimensional acoustic topological insulator

“…Some signatures of these modes have been found in real materials through conductivity measurements [25] and local density of states measurements [26]. Classical wave systems such as photonic crystals and acoustic crystals have been used to demonstrate localized modes bound to dislocations in 2D photonic Chern insulators [27] and weak 2D magnetomechanical TIs [28], disclination waveguiding in 2D valley photonic crystals [16], and fractional mode density at lattice defects in 2D topological crystalline insulators [29,30]. However, the topological helical modes induced by a screw dislocation in a 3D TI [5] have not previously been realized.…”