论文标题
旋转轨道诱导的拓扑拓扑扁平带，是双方晶格的线条和分裂图
Spin-Orbit-Induced Topological Flat Bands in Line and Split Graphs of Bipartite Lattices
论文作者
论文摘要
拓扑平面带，例如扭曲的双层石墨烯中的乐队，正在成为研究相关物理，超导性和运输等主题的有前途的平台。在这项工作中，我们引入了一种通用方法，用于构建二维（2D）拓扑式准式式灯光频段，并从界限图和两部分晶格的拆分图中构造。两分晶格的线图或拆分图显示了一组平面带和一组分散带。平面带在某种程度上通过退化状态连接到分散带。我们发现，随着旋转轨道耦合（SOC），平面带变成准灯，并从色散带中散发出来。 By studying a series of specific line graphs and split graphs of bipartite lattices, we find that (i) if the flat band (without SOC) has inversion or $C_2$ symmetry and is non-degenerate, then the resulting quasi-flat band must be topologically nontrivial, and (ii) if the flat band (without SOC) is degenerate, then there exists an SOC potential such that the resulting quasi-flat band is在拓扑上是非平凡的。这种通用机制是在2D晶体材料和元材料中找到拓扑准纸条带的范式。
Topological flat bands, such as the band in twisted bilayer graphene, are becoming a promising platform to study topics such as correlation physics, superconductivity, and transport. In this work, we introduce a generic approach to construct two-dimensional (2D) topological quasi-flat bands from line graphs and split graphs of bipartite lattices. A line graph or split graph of a bipartite lattice exhibits a set of flat bands and a set of dispersive bands. The flat band connects to the dispersive bands through a degenerate state at some momentum. We find that, with spin-orbit coupling (SOC), the flat band becomes quasi-flat and gapped from the dispersive bands. By studying a series of specific line graphs and split graphs of bipartite lattices, we find that (i) if the flat band (without SOC) has inversion or $C_2$ symmetry and is non-degenerate, then the resulting quasi-flat band must be topologically nontrivial, and (ii) if the flat band (without SOC) is degenerate, then there exists an SOC potential such that the resulting quasi-flat band is topologically nontrivial. This generic mechanism serves as a paradigm for finding topological quasi-flat bands in 2D crystalline materials and meta-materials.
