Topological and Stacked Flat Bands in Bilayer Graphene with a Superlattice Potential
Topological and Stacked Flat Bands in Bilayer Graphene with a Superlattice Potential
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DOI：
10.1103/physrevlett.130.196201
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发表时间：
2023-05-12
影响因子：
8.6
通讯作者：
Cano, Jennifer
中科院分区：
文献类型：
--
作者：
Ghorashi, Sayed Ali Akbar;Dunbrack, Aaron;Cano, Jennifer
我们表明，在二维超晶格势的存在下，双层石墨烯提供了一个高度可调的设置，可以实现各种平带现象。我们重点关注两种制度：（i）具有非零Chern数C的拓扑平坦带，包括具有更高Chern数ICI > 1的带，以及（ii）由C = 0的几乎完美平坦带的堆叠组成的前所未有的相。对于潜在的和超晶格周期性的现实值，这个堆栈可以跨越近100 meV，几乎涵盖了所有的低能谱。我们进一步表明，在拓扑制度，拓扑平坦带具有良好的能带几何实现分数陈绝缘体（FCI），并使用精确对角化，以表明FCI实际上是基态在1/3填充。我们的研究结果提供了一个现实的指导，为未来的实验，实现一个新的平台，平带现象。
We show that bilayer graphene in the presence of a 2D superlattice potential provides a highly tunable setup that can realize a variety of flat band phenomena. We focus on two regimes: (i) topological flat bands with nonzero Chern numbers, C, including bands with higher Chern numbers ICI > 1 and (ii) an unprecedented phase consisting of a stack of nearly perfect flat bands with C = 0. For realistic values of the potential and superlattice periodicity, this stack can span nearly 100 meV, encompassing nearly all of the low-energy spectrum. We further show that in the topological regime, the topological flat band has a favorable band geometry for realizing a fractional Chern insulator (FCI) and use exact diagonalization to show that the FCI is in fact the ground state at 1/3 filling. Our results provide a realistic guide for future experiments to realize a new platform for flat band phenomena.