Flat band and many-body gap in chirally twisted triple bilayer graphene

In this study, we experimentally explore the band structure of chirally twisted triple bilayer graphene, a moir\'e system consisting of three helically stacked Bernal bilayer graphene. We verify the existence of flat bands at the charge neutral point and accurately measure the gaps both between these flat bands and between the flat and the dispersive bands via capacitance measurements. Furthermore, we discover a finite gap even in the absence of an external perpendicular electric field, potentially driven by Coulomb interactions. Our comprehensive analysis offers robust evidence for the existence of flat bands and reveals intriguing physical phenomena.