Tuning the Electronic Properties of Rotated Graphene on Ni(111) by Nickel Carbide Intercalation

High-temperature-deposited rotated graphene (Gr) on Ni(111) has been investigated by in situ scanning tunneling microscopy and spectroscopy at room temperature. The rotated Gr exhibits weak bonding to the Ni(111) surface, which facilitates formation of Ni2C or a second Gr layer underneath via bulk carbon segregation. Areas of rotated Gr present a bias voltage dependence of the apparent amplitude of Gr superlattice corrugations. We find that Ni2C underneath rotated Gr introduces additional electronic features that vary with the gap resistance, which could be related to an orientation-dependent interaction between Ni2C and Gr. Furthermore, the exposure to oxygen has a significant influence on the local density of states of Gr/Ni2C, other than on Ni(111) covered with nonrotated Gr.