Topological minibands and interaction driven quantum anomalous Hall state in topological insulator based moiré heterostructures
Topological minibands and interaction driven quantum anomalous Hall state in topological insulator based moiré heterostructures
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DOI：
10.1038/s41467-024-46717-7
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发表时间：
2024-03-26
影响因子：
16.6
通讯作者：
Liu，Chao-Xing
中科院分区：
文献类型：
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作者：
Yang，Kaijie;Xu，Zian;Liu，Chao-Xing
我们研究了在莫尔e超晶格势下拓扑绝缘体薄膜的电子带结构和拓扑性质，以寻找二维非平凡孤立的微带。为了对该系统进行建模，我们假设在块带隙内存在费米能量，从而考虑一个有效的模型哈密顿量，只有两个表面态位于上下表面，并且彼此强杂化。在拓扑绝缘体薄膜上的另一层二维绝缘材料产生了莫尔e势。在该模型中，当莫尔e势的最小值（最大值）近似形成具有六重旋转对称的六边形晶格时，最低导通（最高价）微带可以是非平凡的。对于非平凡的传导小带情况，两个最低Kramers‘对的传导小带在反转存在时都具有非平凡不变量，而施加外部栅极电压来打破反转会导致只有最低Kramers’对的小带在拓扑上是非平凡的。库仑相互作用可以驱动最低导率的克雷默迷你带在半填充时进入量子反常霍尔态，并通过打破反转对称进一步稳定。基于第一性原理计算的结果，我们提出了SbTethin薄膜的单层Sbon顶部来实现我们的模型。
We studied electronic band structure and topological property of a topological insulator thin film under a moir\'e superlattice potential to search for two-dimensional (2D)non-trivial isolated mini-bands. To model this system, we assume the Fermi energy inside the bulk band gap and thus consider an effective model Hamiltonian with only two surface states that are located at the top and bottom surfaces and strongly hybridized with each other. The moir\'e potential is generated by another layer of 2D insulating materials on top of topological insulator films. In this model, the lowest conduction (highest valence) mini-bands can benon-trivial when the minima (maxima) of the moir\'e potential approximately forms a hexagonal lattice with six-fold rotation symmetry. For the nontrivial conduction mini-band cases, the two lowest Kramers' pairs of conduction mini-bands both have nontrivialinvariant in presence of inversion, while applying external gate voltages to break inversion leads to only the lowest Kramers' pair of mini-bands to be topologically non-trivial. The Coulomb interaction can drive the lowest conduction Kramers' mini-bands into the quantum anomalous Hall state when they are half-filled, which is further stabilized by breaking inversion symmetry. We propose the monolayer Sbon top of SbTethin films to realize our model based on results from the first principles calculations.