Electronic and magnetic properties of graphene densely decorated with 3d metallic adatoms—the effect of structure privilege and spin–orbit interaction

Abstract

The electronic properties of graphene decorated with Ni, Co, Cu and Zn adatoms in the presence of the spin–orbit interaction are studied using the density functional theory approach. We focus on the case when the indicated 3d metallic adatoms form a perfect, close-packed single-atomic layer above the graphene surface. The two configurations are examined, namely the adatoms in the on-top, and the hollow positions on graphene. We show that despite relatively small values of the binding energies, suggesting rather a physisorbtion of the adatomic layers on graphene, the p − d orbital hybridization at the graphene-adatomic layer interface arises. The arisen orbital hybridization results in the charge transfer that takes place from the adatomic layer to the graphene, and in a consequence the graphene becomes n-doped. The proximity of metallic adatoms modifies also the magnetic state of graphene. This effect is especially pronounced for the decoration with magnetic atoms, when the magnetic moments of the considerable values are induced on the graphene sublattices. The analysis of the band structure demonstrates that the charge transfer, as well as the related induced magnetism on graphene, modify the graphene electronic properties, especially near high symmetry points and importantly the Dirac cones. The presence of the metallic adatoms breaks the graphene symmetry and splits the bands due to the exchange coupling. We show that for the hollow configuration the gap opening arises at the point due to the Rashba-like spin–orbit interaction, while in the case of the on-top configuration the energy gap opens mainly due to the staggered potential. We also mapped the parameters of an effective Hamiltonian on the results obtained with the density functional theory approach.