arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2006.04817cond-mat.mes-hall
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位错作为高阶拓扑绝缘体的体探针

Dislocation as a bulk probe of higher-order topological insulators

Bitan Roy, Vladimir Juricic

摘要:

拓扑材料是现代凝聚态物理研究的中心,它以其坚固的金属边缘或表面态为拓扑不变量,表征了体材料中的电子能带结构。高阶拓扑(HOT)状态扩展了这种通常的体边界对应关系,因此它们拥有位于低维边界(如角和铰链)的模式。在这里,我们从理论上证明,位错,晶体材料中无处不在的缺陷,可以探测高阶拓扑结构,最近在各种平台上实现。我们发现,HOT绝缘体响应位错通过对称性保护的有限能量的间隙电子模式,定位在缺陷的核心,这源于HOT质量畴壁的取向和伯格斯矢量的位错之间的相互作用。因此,只有当Burgers矢量指向低维无间隙边界时,这些模式才变得无间隙。我们的研究结果是相应的系统探测的扩展体边界对应在广泛的HOT晶体,光子和声子或机械超材料通过体拓扑晶格缺陷。

英文摘要:

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.

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