▎ 摘　　要

Magnetism and the mechanism of magnetic coupling in graphene decorated with monovalent and divalent adsorbates were investigated using first-principles calculations based on spin polarized density functional theory. The effects of adsorption concentration and the electronegativity of the adsorbate species on the magnetic and electronic properties were analyzed. For monovalent chemisorptions, the magnetic order originates from the instability of pi electrons induced by the adsorption, opening a narrow energy gap and resulting in antiparallel spin directions on adjacent carbon atoms on the graphene sheet. The magnetic order is only possible for the separation between the adsorbing sites less than 10 angstrom. On the contrary, divalent chemisorptions cause long-range magnetic coupling, which is originated from the exchange interactions between localized nonbonding pi electrons (spin-polarized) mediated by the conduction pi electrons around the Fermi energy, similar to the s-d interaction in transition metals. We demonstrate that our results are well consistent with recent experimental findings.