On magic angles and band flattening in twisted bilayer graphene

Understand

When two graphene layers are rotated from AA or AB configuration by a small angle, the band structure changes dramatically.

• Numerical calculations have shown that, at certain discrete angles called magic angles, the low energy bands become flat leading to localization of electrons.
• The origin of this strange behavior, however, is not well understood.
• Here, I propose a theory that offers an understanding of the phenomenon, focusing on the first magic angle.