论文标题
在扭曲的双层石墨烯晶格模型中实现拓扑莫特绝缘子
Realization of Topological Mott Insulator in a Twisted Bilayer Graphene Lattice Model
论文作者
论文摘要
魔术角扭曲的双层石墨烯最近已成为一个蓬勃发展的材料平台，实现了相关的电子现象，发生在其拓扑平坦的频带内。已经应用了几种数值和分析方法来了解其中的相关阶段，从而揭示了与量子霍尔物理学的相似之处。在这项工作中，我们为TBG系统提供了Mott-Hubbard的观点。我们仅在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新归一化组，我们确定了绝缘条带相和量子异常霍尔状态之间的一阶量子相变，其Chern数量为$ \ pm pm 1 $。我们的结果不仅阐明了在四分之三填充处发现的量子异常霍尔状态的机制，而且还提供了一个拓扑莫特绝缘子的例子，即，在强耦合极限下，量子异常霍尔状态。
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 $\pm 1$. 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.
