Superconductivity in bilayer graphene intercalated with alkali and alkaline earth metals

With the enormous research activity focused on graphene in recent years, it is not surprising that graphene superconductivity has become an attractive area of research. To date, no superconducting properties have been experimentally observed in the pristine form of graphene but controllable structure manipulation is a promising way to induce a superconducting state in graphene-based systems. Therefore, herein we investigate the possible superconductivity in two-layer graphene intercalated with atoms of alkali and alkaline earth metals. Results of our calculations conducted within the framework of density functional theory combined with the Eliashberg theory allow us to conclude that the Cooper pairing in these superconductors can be described in a standard phonon-mediated scenario. In this regime, C6XC6 (X = K, Ca, Rb and Sr) are expected to be superconductors with estimated superconducting critical temperatures of 5.47-14.56 K and with the ratios of energy gap to transition temperature exceeding the value predicted by the Bardeen-Cooper-Schrieffer theory.