The electron band structure of manganese-adsorbed graphene on an SiC(0001)
substrate has been studied using angle-resolved photoemission spectroscopy.
Upon introducing manganese atoms, the conduction band of graphene completely
disappears and the valence band maximum is observed at 0.4 eV below Fermi
energy. At the same time, the slope of the valence band decreases, approaching
the electron band structure calculated using the local density approximation
method. While the former provides experimental evidence of the formation of
nearly free-standing graphene on an SiC substrate, concomitant with a
metal-to-insulator transition, the latter suggests that its electronic
correlations can be modified by foreign atoms. These results pave the way for
promising device applications using graphene that is semiconducting and charge
neutral.Comment: 16 pages, 3 figure
