‘Magic-angle’ graphene doubles up

Two years ago a team of researchers at the Massachusetts Institute of Technology (MIT) in the US kicked off the field of “twistronics” by discovering that two layers of graphene offset by a small angle could support an array of insulating and superconducting electron states. This novel electronic platform, dubbed “magic-angle” graphene, heralded the beginning of a fundamentally new approach to device engineering. Now the researchers, again led by Pablo Jarillo-Herrero, have extended the “magic” twist to another graphene system: twisted bilayer-bilayer graphene, made from misaligned stacks of bilayer sheets of atom-thick carbon instead of monolayer ones. The system, which can be tuned by applying an electric field, could be used to investigate the strong electron-electron interactions that lead to phenomena such as high-temperature superconductivity and correlated quantum phases.