External Electric Field Modulation of Structural Configurations and Electronic Properties of Gold Dimers on Graphene

By use of first-principles calculations, we study the effects of the external electric field F on the structural configurations and electronic properties of gold dimers on graphene. The direction of the applied F is perpendicular to the graphene plane, and the downward (upward) direction is defined as a positive (negative) one. It is shown that the adsorption energy increases with increasing F regardless of its direction owing to an enhancement of the charge transfer between the gold dimers and the graphene. The crossover of adsorbed configurations induced by F is predicted. For F >= -0.1 V/angstrom, an optimal vertical gold dimer on graphene is determined, whereas for F < -0.1 V/angstrom, the preferred adsorbed configuration of the gold dimer is parallel to the graphene plane. The physical mechanism behind F control of the adsorption of gold dimers deposited on graphene is also discussed in detail. The present results indicate the key role of F as an effective means in tuning the interactions between gold atoms and graphene.