They probed the bandstructure at BESSY II with extremely high resolution ARPES and could identify a flat area at a surprising location.

Above – The data show that In the case of the two-layer graphene, a flat part of bandstructure only 200 milli-electron volts below the Fermi energy. Credit: HZB

A complicated option for superconductivity

In April 2018, a group at MIT, USA, showed that it is possible to generate a form of superconductivity in a system of two layers of graphene under very specific conditions: To do this, the two hexagonal nets must be twisted against each other by exactly the magic angle of 1.1°. Under this condition a flat band forms in the electronic structure. The preparation of samples from two layers of graphene with such an exactly adjusted twist is complex, and not suitable for mass production. Nevertheless, the study has attracted a lot of attention among experts.