论文标题
扭曲的单层双层石墨烯中的拓扑平坦带和相关状态
Topological Flat Bands and Correlated States in Twisted Monolayer-Bilayer Graphene
论文作者
论文摘要
单层石墨烯放置在AB堆叠的双层石墨烯顶部的扭曲上，托管拓扑平坦带有各种扭曲角度。这些频段的分散以及它们之间的间隙可以通过垂直电场有效地控制，从而诱导拓扑转变，并伴随着Chern数字的变化。在施加的电场诱导平坦带之间间隙的状态下，我们发现浆果曲率的分布相对均匀。因此，在整数填充因子上，相互作用诱导的山谷和/或自旋极化状态在能量上是有利的。特别是，我们预测一个量子异常的霍尔状态在填充因子$ν= 1 $，twist Angles $ 1^\ Circ <θ<1.4^\ Circ $。此外，为了表征系统对磁场的响应，我们计算了Hofstadter Butterfly和Wannier图，这些图可用于探测该材料中平坦带的分散和拓扑。
Monolayer graphene placed with a twist on top of AB-stacked bilayer graphene hosts topological flat bands in a wide range of twist angles. The dispersion of these bands and gaps between them can be efficiently controlled by a perpendicular electric field, which induces topological transitions accompanied by changes of the Chern numbers. In the regime where the applied electric field induces gaps between the flat bands, we find a relatively uniform distribution of the Berry curvature. Consequently, interaction-induced valley- and/or spin-polarized states at integer filling factors are energetically favorable. In particular, we predict a quantum anomalous Hall state at filling factor $ν=1$ for a range of twist angles $1^\circ<θ<1.4^\circ$. Furthermore, to characterize the response of the system to magnetic field, we computed the Hofstadter butterfly and the Wannier plot, which can be used to probe the dispersion and topology of the flat bands in this material.
