Abstract
A possible approach to achieve quasi-freestanding graphene on a substrate for technological purpose is the intercalation of alkali metal atoms. Cs intercalation between graphene and Ni(111) therefore is investigated using density functional theory, incorporating van der Waals corrections. It is known that direct contact between graphene and Ni(111) perturbs the Dirac states. We find that Cs intercalation restores the linear dispersion characteristic of Dirac fermions, which agrees with experiments, but the Dirac cone is shifted to lower energy, i.e., the graphene sheet is n-doped. Cs intercalation therefore decouples the graphene sheet from the substrate except for a charge transfer. On the other hand, the spin polarization of Ni(111) does not extend through the intercalated atoms to the graphene sheet, for which we find virtually spin-degeneracy.
Highlights
A possible approach to achieve quasi-freestanding graphene on a substrate for technological purpose is the intercalation of alkali metal atoms
Graphene is gaining attention for its unique two-dimensional structure and special electronic properties, which are interesting for many applications[1]
A popular method to prepare graphene in high quality and large scale is chemical vapor deposition[2], which has been successfully used for metallic substrates, such as Cu3, Au4, Co5, Ni6, Pd7, and Ir8
Summary
A possible approach to achieve quasi-freestanding graphene on a substrate for technological purpose is the intercalation of alkali metal atoms. The small distance (2.1 Å) realized between graphene and Ni(111) results in significant hybridization of the Ni 3d and C 2p orbitals, which explains the strong modification of the band structure[14,15] It has been shown experimentally[16] and theoretically[17] that C magnetic moments are induced. Intercalation of noble metal atoms can restore the original band structure to give rise to quasi-freestanding graphene[18]. Alkali metals have been studied experimentally[11] and theoretically[21] They weaken the interaction between graphene and Ni(111) by enlarging the interlayer distance[22,23]. We consider the structural, electronic, and magnetic properties of graphene on Ni(111), using density functional theory, and analyze the changes when intercalating the system with different concentrations of Cs atoms. Cs is an alkali metal with one electron in its outer shell and strongly favors a Cs+1 state, so that it does not participate in chemical bonding but acts purely as spacer
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