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成为一种蓬勃发展的材料平台，实现了在其拓扑平带内发生的相关电子现象。已经应用了几种数值和分析方法来理解其中的相关相，揭示了与量子霍尔物理学的一些相似之处。在这项工作中，我们为 TBG 系统提供了 Mott-Hubbard 视角。在仅包含投影库仑相互作用的晶格模型上使用大规模密度矩阵重整化群，我们确定了绝缘条纹相和量子反常霍尔态之间的一阶量子相变，其陈数为 ±1。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，