High-temperature surface superconductivity in rhombohedral graphite
  Surface superconductivity in rhombohedral graphite is a robust phenomenon which can exist even when higher order hoppings between the layers lift the topological protection of the surface flat band and introduce a quadratic dispersion of electrons with a heavy effective mass. We show that for weak pairing interaction, the flat band character of the surface superconductivity transforms into a BCS-like relation with high critical temperature characterized by a higher coupling constant due to a much larger density of states than in the bulk. Our results offer an explanation for the recent findings of graphite superconductivity with an unusually high transition temperature. 
N. B. Kopnin, M. Ij\"as, A. Harju, and T. T. Heikkil\"a
cond-mat.supr-con cond-mat.mtrl-sci