Researchers discover how to make graphene superconducting

First discovered in at the University of Manchester by Professors Andre Geim and Konstatin Novoselov, graphene is the thinnest, strongest and most conductive material ever discovered. Around 200 times stronger than steel yet just one atom thick, it has a wide range of potential applications, including ultra fast transistors, sensors and even transparent electrodes. The classic way to make graphene is by peeling atomically thin sheets from a block of graphite, but scientists can also isolate these carbon sheets by chemically interweaving graphite with crystals of pure calcium. The result, known as calcium intercalated graphite (CaC6), consists of alternating one-atom-thick layers of graphene and calcium. The discovery that CaC6 is superconducting set off a wave of excitement, but in nearly a decade of trying, researchers have been unable to tell whether CaC6's superconductivity came from the calcium layer, the graphene layer or both. Now, by using a beam of intense ultraviolet light to look deep into the electronic structure of the material, a team from the Department of Energy's SLAC National Accelerator Laboratory, in collaboration with Stanford University, has found that the graphene layers are in fact instrumental in making CaC6 superconductive. During their investigation, the researchers saw how electrons scatter back and forth between graphene and calcium, interact with natural vibrations in the material's atomic structure and pair up to conduct electricity without resistance. "With this technique, we can show for the first time how the electrons living on the graphene planes actually superconduct," said graduate student Jonathan Sobota. "The calcium layer also makes crucial contributions. Finally we think we understand the superconducting mechanism in this material."