Visualization of the flat electronic band in twisted bilayer graphene near the magic angle twist

Understand

Bilayer graphene was theorized to host a moire miniband with flat dispersion if the layers are stacked at specific twist angles known as the magic angles.

• Recently, such twisted bilayer graphene (tBLG) with the first magic angle twist was reported to exhibit correlated insulating state and superconductivity, where the presence of the flat miniband in the system is thought to be essential for the emergence of these ordered phases in the transport measurements.
• Tunneling spectroscopy and electronic compressibility measurements in tBLG have revealed a van Hove singularity that is consistent with the presence of the flat miniband.
• However, a direct observation of the flat dispersion in the momentum-space of such moire miniband in tBLG is still elusive.