标题： 独立可调的石墨烯双莫尔系统中的平带和关联性 显示英文标题

标题： Independently Tunable Flat Bands and Correlations in a Graphene Double Moiré System

摘要： 我们报告了一个由四层石墨烯组成的双莫尔系统，其中顶部和底部对形成小扭转角的双层石墨烯，而中间界面存在大的旋转错位。 该系统显示出与顶部和底部扭曲双层石墨烯（TBG）子系统相关的两组空间分离的平坦带的清晰特征，每个子系统均可独立调节。 热力学分析揭示了层之间的弱关联，使得可以测量每个组成TBG的载流子密度作为化学势函数。 我们发现，在每个莫尔单元胞中整数电子数的关联绝缘态在魔角附近最为稳定，而在中性点的间隙态在较大扭转角时更为稳定。 显示英文摘要

摘要： We report on a double moir\'e system consisting of four graphene layers, where the top and bottom pairs form small-twist-angle bilayer graphene, and the middle interface has a large rotational mismatch. This system shows clear signatures of two sets of spatially separated flat bands associated with the top and bottom twisted bilayer graphene (TBG) subsystems, each independently tunable. Thermodynamic analysis reveals weak correlations between layers that allow the chemical potential to be measured as a function of carrier density for each constituent TBG. We find that correlated insulating states at integer number of electrons per moir\'e unit cell are most robust near magic angle, whereas gapped states at neutrality are more robust at larger twist angles.