Direct evidence for flat bands in twisted bilayer graphene from nano-ARPES

Understand

Transport experiments in twisted bilayer graphene revealed multiple superconducting domes separated by correlated insulating states.

• These properties are generally associated with strongly correlated states in a flat mini-band of the hexagonal moir\'e superlattice as it was predicted by band structure calculations.
• Evidence for such a flat band comes from local tunneling spectroscopy and electronic compressibility measurements, reporting two or more sharp peaks in the density of states that may be associated with closely spaced van Hove singularities.
• Direct momentum resolved measurements proved difficult though.