论文标题

涡度:理想分数Chern绝缘子的统一标准

Vortexability: A Unifying Criterion for Ideal Fractional Chern Insulators

论文作者

Ledwith, Patrick J., Vishwanath, Ashvin, Parker, Daniel E.

论文摘要

分数Chern绝缘子意识到具有Chern带的晶体系统中分数量子厅效应(FQHE)的显着物理。已知最低的Landau级别(LLL)托管FQHE,但并非所有Chern频段都适合实现分数Chern绝缘子(FCI)。以前的稳定FCI的方法集中在模仿LLL通过动量空间标准。相反,我们通过介绍涡度性概念来采取真实空间的视角。可涡流的Chern乐队接纳了一个固定的操作员,该操作员将涡流引入任何带波功能,同时将状态完全保存在同一频段内。可涡流的乐队接纳了FCI州的试验波形,类似于Laughlin州。在没有色散和足够短的相互作用的情况下,这些FCI状态是基态 - 与浆果曲率的分布无关。可涡流的带比LLL更一般,我们展示了构造它们的食谱。我们在具有或没有磁场的基于石墨烯的系统中表现出不同的例子,并且具有任何Chern号。一类特殊的可涡流带被证明等同于动量空间“痕量条件”或“理想的频带条件”。此外,我们还确定了超出此标准的涡度性的一种更通用的涡度性。我们引入了一种修改的度量,该方法量化了与一般涡度性偏差的偏差,该旋转性可以应用于通用Chern频段以识别有希望的FCI平台。

Fractional Chern insulators realize the remarkable physics of the fractional quantum Hall effect (FQHE) in crystalline systems with Chern bands. The lowest Landau level (LLL) is known to host the FQHE, but not all Chern bands are suitable for realizing fractional Chern insulators (FCI). Previous approaches to stabilizing FCIs focused on mimicking the LLL through momentum space criteria. Here instead we take a real-space perspective by introducing the notion of vortexability. Vortexable Chern bands admit a fixed operator that introduces vortices into any band wavefunction while keeping the state entirely within the same band. Vortexable bands admit trial wavefunctions for FCI states, akin to Laughlin states. In the absence of dispersion and for sufficiently short ranged interactions, these FCI states are the ground state -- independent of the distribution of Berry curvature. Vortexable bands are much more general than the LLL, and we showcase a recipe for constructing them. We exhibit diverse examples in graphene-based systems with or without magnetic field, and with any Chern number. A special class of vortexable bands is shown to be equivalent to the momentum space "trace condition" or "ideal band condition". In addition, we also identify a more general form of vortexability that goes beyond this criterion. We introduce a modified measure that quantifies deviations from general vortexability which can be applied to generic Chern bands to identify promising FCI platforms.

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