Salib Daniel J, Juričić Vladimir, Roy Bitan
Department of Physics, Lehigh University, Bethlehem, PA, 18015, USA.
Departamento de Física, Universidad Técnica Federico Santa María, Casilla 110, Valparaiso, Chile.
Sci Rep. 2023 Sep 15;13(1):15308. doi: 10.1038/s41598-023-42279-8.
Topological lattice defects, such as dislocations and grain boundaries (GBs), are ubiquitously present in the bulk of quantum materials and externally tunable in metamaterials. In terms of robust modes, localized near the defect cores, they are instrumental in identifying topological crystals, featuring the hallmark band inversion at a finite momentum (translationally active type). Here we show that the GB superlattices in both two-dimensional and three-dimensional translationally active higher-order topological insulators harbor a myriad of dispersive modes that are typically placed at finite energies, but always well-separated from the bulk states. However, when the Burgers vector of the constituting edge dislocations points toward the gapless corners or hinges, both second-order and third-order topological insulators accommodate self-organized emergent topological metals near the zero energy (half-filling) in the GB mini Brillouin zone. We discuss possible material platforms where our proposed scenarios can be realized through the band-structure and defect engineering.
拓扑晶格缺陷，如位错和晶界，普遍存在于量子材料的主体中，并且在超材料中是外部可调节的。就稳健模式而言，它们局域在缺陷核心附近，有助于识别拓扑晶体，其特征是在有限动量处存在标志性的能带反转（平移活性类型）。在这里，我们表明，二维和三维平移活性高阶拓扑绝缘体中的晶界超晶格包含大量色散模式，这些模式通常处于有限能量，但总是与体态很好地分离。然而，当构成边缘位错的伯格斯矢量指向无隙角或铰链时，二阶和三阶拓扑绝缘体在晶界小布里渊区的零能量（半填充）附近都容纳自组织出现的拓扑金属。我们讨论了通过能带结构和缺陷工程可以实现我们提出的情景的可能材料平台。
