Graphene on the way to superconductivity

Scientists at HZB have found evidence that double layers of graphene have a property that may let them conduct current completely without resistance. They probed the band structure at BESSY II with extremely high resolution ARPES and could identify a flat area at a surprising location. Their research is published in Science Advances.

Carbon atoms can form bonds in multiple ways. Pure carboncantherefore occur in many forms, including diamond, graphite, nanotubes, football molecules or as a honeycomb net with hexagonal meshes, known as graphene. This exotic, strictly two-dimensional material conducts electricity well, but is not a superconductor. But perhaps this can be changed.

In April 2018, a group at MIT in the U.S. 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 at a1.1 degree angle. 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.