Dislocation as a bulk probe of higher-order topological insulators,Physical Review Research

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Dislocation as a bulk probe of higher-order topological insulators
Physical Review Research ( IF 3.5 ) Pub Date : 2021-07-30 , DOI: 10.1103/physrevresearch.3.033107
Bitan Roy ₁ , Vladimir Juričić _{2,

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Affiliation

Topological materials occupy the central stage in the modern condensed matter physics because of their robust metallic edge or surface states protected by the topological invariant, characterizing the electronic band structure in the bulk. Higher-order topological (HOT) states extend this usual bulk-boundary correspondence, so they host the modes localized at lower-dimensional boundaries, such as corners and hinges. Here we theoretically demonstrate that dislocations, ubiquitous defects in crystalline materials, can probe higher-order topology, recently realized in various platforms. We uncover that HOT insulators respond to dislocations through symmetry protected finite-energy in-gap electronic modes, localized at the defect core, which originate from an interplay between the orientation of the HOT mass domain wall and the Burgers vector of the dislocation. As such, these modes become gapless only when the Burgers vector points toward lower-dimensional gapless boundaries. Our findings are consequential for the systematic probing of the extended bulk-boundary correspondence in a broad range of HOT crystals and photonic and phononic or mechanical metamaterials through the bulk topological lattice defects.

中文翻译：

位错作为高阶拓扑绝缘体的体探针

拓扑材料占据现代凝聚态物理学的中心阶段，因为它们坚固的金属边缘或表面状态受到拓扑不变量的保护，表征了体中的电子能带结构。高阶拓扑 (HOT) 状态扩展了这种通常的体边界对应关系，因此它们承载了位于低维边界（例如角和铰链）处的模式。在这里，我们从理论上证明了位错，晶体材料中普遍存在的缺陷，可以探测最近在各种平台中实现的高阶拓扑。我们发现热绝缘体通过对称保护的有限能量带隙电子模式响应位错，位于缺陷核心，这源于热质量畴壁的方向和位错的伯格斯矢量之间的相互作用。因此，只有当 Burgers 向量指向低维无间隙边界时，这些模式才会变得无间隙。我们的发现对于通过体拓扑晶格缺陷系统探测广泛的热晶体和光子和声子或机械超材料中的扩展体边界对应关系具有重要意义。

更新日期：2021-08-01

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