Superconductivity in twisted bilayer graphene

When two graphene lattices are overlaid and tilted, they can interfere to create a moiré pattern with a long period. At a small angle of about 1 degree, it was recently showed that the energy dispersion of electrons becomes flat and the interaction parameter becomes large. By tuning the carrier density and the magnetic field, the twisted bilayer graphene features different states, including unconventional superconductivity, orbital magnetism, and topological insulators. Compared to other quantum materials, twisted bilayer graphene has the advantage to be based on monolayer graphene, a system with a band structure that is simple and well understood. In addition, the Fermi energy can be tuned by simply adjusting the voltage applied to the gate electrode in order to characterize the whole phase diagram of electrons. We will use innovative approaches to explore the different states of twisted bilayer graphene.