论文标题
扭曲双层石墨烯的魔法角接近相称：朝向超魔术政权
Magic angles in twisted bilayer graphene near commensuration: Towards a hypermagic regime
论文作者
论文摘要
Bistritzer-Macdonald Continuum模型（BM模型）描述了小型扭曲角度的扭曲双层石墨烯（TBG）的低能Moiré带。我们在任何相称的扭曲角度附近得出了TBG的广义连续模型，该模型的特征是相应的$ aa $堆栈（而不是BM模型中的真正跳跃），这是一个真正的层间跳跃器，这是一个真正的层间跳跃$ ab/ba $ stackings，以及全球能量转移。 $ aa $堆叠跳和扭转角的复杂阶段定义单个角度参数$ ϕ_0 $。我们计算前六个不同的相应TBG配置的模型参数，其中38.2^\ Circ $配置可能在实验可观察到的能量尺度内。我们在类似于BM型号的条件下，在任何$ ϕ_0 $的情况下确定第一个魔术角。在这个角度，除了$ \boldsymbolγ_m$ $ $ $ $ $ \boldsymbolγ_M$点外，最低的两个Moiré频段变得平坦，并保留了脆弱的拓扑，但失去了粒子孔对称性。我们进一步确定了一个以$ ϕ_0 = \pmπ/2 $为中心的超魔法参数制度，其中许多Moiré乐队周围的电荷中立性（通常$ 8 $或更多）同时变得平坦。这些平坦的乐队中的许多类似于Kagome晶格和$ p_x $，$ P_Y $ 2-键2-蜂窝状晶格紧密结合模型。
The Bistritzer-MacDonald continuum model (BM model) describes the low-energy moiré bands for twisted bilayer graphene (TBG) at small twist angles. We derive a generalized continuum model for TBG near any commensurate twist angle, which is characterized by complex interlayer hoppings at commensurate $AA$ stackings (rather than the real hoppings in the BM model), a real interlayer hopping at commensurate $AB/BA$ stackings, and a global energy shift. The complex phases of the $AA$ stacking hoppings and the twist angle together define a single angle parameter $ϕ_0$. We compute the model parameters for the first six distinct commensurate TBG configurations, among which the $38.2^\circ$ configuration may be within experimentally observable energy scales. We identify the first magic angle for any $ϕ_0$ at a condition similar to that of the BM model. At this angle, the lowest two moiré bands at charge neutrality become flat except near the $\boldsymbolΓ_M$ point and retain fragile topology but lose particle-hole symmetry. We further identify a hypermagic parameter regime centered at $ϕ_0 = \pmπ/2$ where many moiré bands around charge neutrality (often $8$ or more) become flat simultaneously. Many of these flat bands resemble those in the kagome lattice and $p_x$, $p_y$ 2-orbital honeycomb lattice tight-binding models.
