Structural and Magnetic Properties of 3d Transition‐Metal‐Atom Adsorption on Perfect and Defective Graphene: A Density Functional Theory Study

We systematically investigate the interactions and magnetic properties of a series of 3d transition‐metal (TM; Sc–Ni) atoms adsorbed on perfect graphene (G₆), and on defective graphene with a single pentagon (G₅), a single heptagon (G₇), or a pentagon–heptagon pair (G₅₇) by means of spin‐polarized density functional calculations. The TM atoms tend to adsorb at hollow sites of the perfect and defective graphene, except for G₆Cr, G₅Cr, and G₅Ni. The binding energies of TMs on defective graphene are remarkably enhanced and show a V‐shape, with G_NCr and G_NMn having the lowest binding energies. Furthermore, complicated element‐ and defect‐dependent magnetic behavior is observed in G_NTM. Particularly, the magnetic moments of G_NTM linearly increase by about 1 μ_B and follow a hierarchy of G₇TM57TM5TM as the TM varies from Sc to Mn, and the magnetic moments begin to decrease afterward; by choosing different types of defects, the magnetic moments can be tuned over a broad range, for example, from 3 to 6 μ_B for G_NCr. The intriguing element‐ and defect‐dependent magnetic behavior is further understood from electron‐ and back‐donation mechanisms.