拓扑杂质带
Topological Impurity Bands
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中文总结 AI 辅助
本文提出随机局域缺陷可形成拓扑杂质带（TIB），诱导新的拓扑相变，即使初始模型为平庸带绝缘体，并通过解析和数值计算验证了该机制。
中文摘要 AI 辅助
无序对物质拓扑相的影响通常表现为要么保持拓扑性，要么破坏拓扑性。例如，量子霍尔效应的量子化和手性边缘模在强无序渗流转变退出拓扑相之前始终保持稳健。无序还可以扩大预先存在的拓扑相，产生拓扑安德森绝缘体（TAI）。然而，TAI及其他理论处理方法依赖于对长波长随机性进行微扰平均，这表明当无序涉及局域缺陷时，可能会出现额外效应。在此，我们证明有限密度的随机分布缺陷能够产生各种新的拓扑相变。这种无序诱导拓扑的途径可视为拓扑杂质带（TIB）的形成，并且即使初始清洁模型是平庸的带绝缘体，该方法也适用。该理论依赖于杂质束缚态的轨道相关涡度，我们在通用狄拉克锥相变附近解析推导了该涡度，并利用Qi-Wu-Zhang和Haldane的陈绝缘体晶格模型进行了验证。在3%缺陷密度下数值计算的相图显示，在截然不同的TIB和TAI区域中存在稳健的拓扑转变，这表明存在一条通往拓扑相的局域途径。
英文摘要
The effects of disorder on topological phases of matter are typically either preservation of topology or its destruction. For example, the quantum Hall effect's quantization and chiral edge mode remain robust until a strong-disorder percolation transition exits the topological phase. Disorder can also enlarge a preexisting topological phase, yielding a topological Anderson insulator (TAI). However, the reliance of TAI and other theoretical treatments on perturbatively averaging out long-wavelength randomness suggests that additional effects might appear when the disorder involves localized defects. Here we show that a finite density of randomly distributed defects can generate various new topological phase transitions. This route to disorder-induced topology can be viewed as the formation of topological impurity bands (TIB) and is applicable even if the initial clean model is a trivial band insulator. The theory relies on an orbital-dependent vorticity of impurity bound states, which we derive analytically near a generic Dirac cone phase transition as well as using the Chern insulator lattice models of Qi-Wu-Zhang and Haldane. Their numerically computed phase diagrams at 3% defect density show robust topological transitions in distinct TIB and TAI regimes, suggesting a local route to topological phases.
发表机构
- School of Physics, Georgia Institute of Technology（佐治亚理工学院物理学院）
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