The Dirac spectrum of bilayer graphene when the two layers are exactly aligned (left) shifts with a slight interlayer twist that breaks interlayer-coupling and potential symmetry, leading to a new spectrum with surprisingly strong signatures in ARPES data. (Image courtesy of Keun Su Kim) Researchers with the U.S. Department of Energy (DOE)’s Lawrence Berkeley National Laboratory (Berkeley Lab) have discovered a unique new twist to the story of graphene, sheets of pure carbon just one atom thick, and in the process appear to have solved a mystery that has held back device development. Electrons can race through graphene at nearly the speed of light – 100 times faster than they move through silicon. In addition to being superthin and superfast when it comes to conducting electrons, graphene is also superstrong and superflexible, making it a potential superstar material in the electronics and photonics fields, the basis for a host of devices, starting with ultrafast transistors. One big problem, however, has been that graphene’s electron  conduction can’t be completely stopped, an essential requirement for on/off devices. The on/off problem stems from monolayers of graphene having no bandgaps – ranges of energy in which no electron states can exist. Without a bandgap,

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