Researchers at Princeton University have experimentally observed the Kekulé spiral state in graphene as predicted by a collaboration of researchers from Zurich (group Neupert), Oxford and Berkeley.
Graphene is one of the best known electrical conductors. When two layers of graphene are stacked with a twist between them, the system can suddenly become insulating. Researchers from Zurich (Neupert group), Oxford and Berkeley recently proposed an explanation to this conundrum: The electrons are locked in an exotic state called a Kekulé spiral that renders them unable to transport electrical current. This has now been vindicated by experiments in Princeton that used a scanning tunnelling microscope to take an image of a Kekulé spiral in this material.