For years many graphene researchers pursued superconductivity. In 2018 Pablo Jarillo-Herrero of MIT and his colleagues found it in so-called magic-angle bilayer graphene (see Physics Today, May 2018, page 15). A single layer of graphene, a two-dimensional sheet of carbon atoms, is not superconducting on its own. But two sheets (blue and black in figure 1) vertically stacked at just the right, “magic” angle θ—about 1.1° with respect to each other—have a superconducting transition around 1.7 K.
Now Dmitri Efetov of the Institute of Photonic Sciences in Barcelona, Spain, and his colleagues have replicated Jarillo-Herrero’s results and discovered a rich landscape of competing states in magic-angle graphene.1 By preparing a more homogenous device, Efetov’s team could establish and resolve previously hidden electronic states