Transport experiments in twisted bilayer graphene have revealed multiple superconducting domes separated by correlated insulating states^1,2,3,4,5. These properties are generally associated with strongly correlated states in a flat mini-band of the hexagonal moiré superlattice as was predicted by band structure calculations^6,7,8. Evidence for the existence of a flat band comes from local tunnelling spectroscopy^{9,10,11,12,13} and electronic compressibility measurements¹⁴, which report two or more sharp peaks in the density of states that may be associated with closely spaced Van Hove singularities. However, direct momentum-resolved measurements have proved to be challenging¹⁵. Here, we combine different imaging techniques and angle-resolved photoemission with simultaneous real- and momentum-space resolution (nano-ARPES) to directly map the band dispersion in twisted bilayer graphene devices near charge neutrality. Our experiments reveal large areas with a homogeneous twist angle that support a flat band with a spectral weight that is highly localized in momentum space. The flat band is separated from the dispersive Dirac bands, which show multiple moiré hybridization gaps. These data establish the salient features of the twisted bilayer graphene band structure.

在扭曲的双层石墨烯中的输运实验已经揭示了被相关的绝缘状态^1,2,3,4,5隔开的多个超导圆顶。这些性质通常与六角形莫尔超晶格的扁平微型带中的强相关状态相关，如带结构计算^6,7,8所预测。存在平坦带的证据来自局部隧穿光谱法^{9,10,11,12,13}和电子可压缩性测量值¹⁴，它们报告了状态密度中的两个或多个尖峰，这些峰可能与紧密间隔的Van Hove奇点有关。但是，直接动量解析测量已被证明具有挑战性¹⁵。在这里，我们结合了不同的成像技术和角度分辨光发射技术，同时实现了真实空间和动量空间分辨率（nano-ARPES），以直接绘制扭曲双层石墨烯器件中接近电荷中性的能带色散。我们的实验揭示了具有均匀扭转角的大区域，该区域支持谱带高度集中在动量空间中的平坦带。平坦带与分散的狄拉克带分开，弥散的狄拉克带显示出多个莫尔杂交间隙。这些数据建立了扭曲的双层石墨烯带结构的显着特征。