Chen Bin-Bin, Liao Yuan Da, Chen Ziyu, Vafek Oskar, Kang Jian, Li Wei, Meng Zi Yang
School of Physics, Beihang University, Beijing, 100191, China.
Department of Physics and HKU-UCAS Joint Institute of Theoretical and Computational Physics, The University of Hong Kong, Pokfulam Road, Hong Kong, China.
Nat Commun. 2021 Sep 16;12(1):5480. doi: 10.1038/s41467-021-25438-1.
Magic-angle twisted bilayer graphene has recently become a thriving material platform realizing correlated electron phenomena taking place within its topological flat bands. Several numerical and analytical methods have been applied to understand the correlated phases therein, revealing some similarity with the quantum Hall physics. In this work, we provide a Mott-Hubbard perspective for the TBG system. Employing the large-scale density matrix renormalization group on the lattice model containing the projected Coulomb interactions only, we identify a first-order quantum phase transition between the insulating stripe phase and the quantum anomalous Hall state with the Chern number of ±1. Our results not only shed light on the mechanism of the quantum anomalous Hall state discovered at three-quarters filling, but also provide an example of the topological Mott insulator, i.e., the quantum anomalous Hall state in the strong coupling limit.
魔角扭曲双层石墨烯最近已成为一个蓬勃发展的材料平台，可实现其拓扑平带内发生的关联电子现象。已经应用了几种数值和分析方法来理解其中的关联相，揭示了与量子霍尔物理的一些相似性。在这项工作中，我们为扭曲双层石墨烯（TBG）系统提供了一个莫特-哈伯德视角。在仅包含投影库仑相互作用的晶格模型上采用大规模密度矩阵重整化群，我们确定了绝缘条纹相和陈数为±1的量子反常霍尔态之间的一级量子相变。我们的结果不仅揭示了在四分之三填充时发现的量子反常霍尔态的机制，还提供了一个拓扑莫特绝缘体的例子，即在强耦合极限下的量子反常霍尔态。
