Phonon-mediated superconductivity in graphene by lithium deposition

Graphene1 is the physical realization of many fundamental concepts and phenomena in solid-state physics2. However, in the list of graphene’s many remarkable properties3–6, superconductivity is notably absent. If it were possible to find a way to induce superconductivity, it could improve the performance and enable more efficient integration of a variety of promising device concepts including nanoscale superconducting quantum interference devices, single-electron superconductor–quantum dot devices7,8, nanometre-scale superconducting transistors9 and cryogenic solid-state coolers10. To this end, we explore the possibility of inducing superconductivity in a graphene sheet by doping its surface with alkaline metal adatoms, in a manner analogous to which superconductivity is induced in graphite intercalated compounds11,12 (GICs). As for GICs, we find that the electrical characteristics of graphene are sensitive to the species of adatom used. However, contrary to what happens in GICs, Li-covered graphene is superconducting at a much higher temperature with respect to Ca-covered graphene. As graphene itself is not superconducting, phonon-mediated superconductivity must be induced by an enhancement of the electron–phonon coupling (λ),