Superconductivity in Graphene-Lithium Systems

We present first-principles calculations on systems consisting of a few layers of graphene and lithium. In particular, we investigate the evolution of the electron-phonon coupling strength with an increasing number of layers. We find that for intercalated systems such as C$_6$-Li-C$_6$ or C$_6$-Li-C$_6$-Li-C$_6$ the electron-phonon coupling is weak. However, for systems of equal number of graphene and lithium layers, such as C$_6$-Li or C$_6$-Li-C$_6$-Li, the electron-phonon coupling is strong. We investigate the optimal configuration that yields the highest superconducting transition temperature.