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首页> 外文期刊>Physical review >Excitonic Laughlin states in ideal topological insulator flat bands and their possible presence in moire superlattice materials
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Excitonic Laughlin states in ideal topological insulator flat bands and their possible presence in moire superlattice materials

机译：激子乐的笑线状态在理想的拓扑绝缘体平带和他们在莫尔超晶格材料中的存在

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摘要

We investigate few- and many-body states in half-filled ideal topological insulator flat bands realized by two degenerate Landau levels which experience opposite magnetic fields. This serves as a toy model of flat bands in moire materials in which valleys have Chern numbers C = ±1. We argue that although the spontaneously polarized Ising Chern magnet is a natural ground state for repulsive Coulomb interactions, it can be in reasonable energetic competition with correlated Laughlin states of excitons when short-distance corrections to interactions are included. This is because charge neutral excitons in these bands behave effectively as charged particles in ordinary Landau levels. In particular, the Ising Chern magnet is no longer the ground state once the strength of a short-range intravalley repulsion is about 30% larger than the intervalley repulsion. Remarkably, these excitonic Laughlin states feature valley number fractionalization but no charge fractionalization and a quantized charge Hall conductivity identical to the Ising magnet, σ_(xy) = ±e~2/h, and thus cannot be distinguished from it by ordinary charge transport measurements. The Laughlin state with the highest density of excitons that can be constructed in these bands is an analog of ⅴ = 1/4 bosonic Laughlin state and has no valley polarization even though it spontaneously breaks time reversal symmetry.
机译：我们调查了由两种堕落的Landau水平实现的半填充理想的拓扑绝缘体平带中的几个身体状态，这些拓扑绝缘体扁平带子在磁场相对的情况下实现。这用作莫尔材料中的扁平带的玩具模型，其中谷谷数C =±1。我们认为，尽管自发的偏振钟磁铁是一种自然的基础态度，用于令人厌恶的库仑相互作用，当包括对交互的短距离校正时，它可以合理地与激子的相关笑声状态。这是因为这些频段中的电荷中性激子在普通Landau水平中的带电粒子有效。特别是，一旦短程静脉内排斥的强度大约比inchalley排斥大约30％，就不再是地面状态。值得注意的是，这些兴奋的笑线状态特征谷数分数化，但没有充电分数化和与ising磁体相同的量化电荷霍尔电导率，σ_（xy）=±e〜2 / h，因此不能通过普通电荷传输测量来区分。具有最高密度的激子密度的Laughlin状态，可以在这些带中构建为ⅴ= 1/4挥霍笑源的模拟，即使它自发地打破时间反转对称性，也没有谷极化。

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  • 来源
    《Physical review》 |2020年第3期|035158.1-035158.10|共10页
  • 作者

    Nikolaos Stefanidis; Inti Sodemann;

  • 作者单位

    Max-Planck Institute for the Physics of Complex Systems D-01187 Dresden Germany;

    Max-Planck Institute for the Physics of Complex Systems D-01187 Dresden Germany;

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