A theoretical study, using density functional calculations, was presented of the structural, electronic and magnetic properties of 3d transition metal, noble metal and Zn atoms interacting with carbon monovacancies in graphene. Particular attention was paid to the electronic and magnetic properties of these substitutional impurities and it was found that they could be fully understood by using a simple model based upon the hybridization between the states of the metal atom, particularly the d shell, and the defect levels associated with an unreconstructed D3h carbon vacancy. Three different regimes were identified which were associated with the occupation of different carbon–metal hybridized electronic levels: (i) bonding states were completely filled for Sc and Ti, and these impurities were non-magnetic; (ii) the non-bonding d shell was partially occupied for V, Cr and Mn and, correspondingly, these impurities present large and localized spin moments; (iii) anti-bonding states with increasing carbon character were progressively filled for Co, Ni, the noble metals and Zn. The spin moments of these impurities oscillate between 0 and 1μB and were increasingly delocalized. The substitutional Zn suffers a Jahn–Teller-like distortion from the C3v symmetry and, as a consequence, had a zero spin moment. Fe occupies a distinct position at the border between regimes (ii) and (iii) and showed a more complex behavior: while it was non-magnetic at the level of generalized gradient approximation calculations, its spin moment could be switched on using generalized gradient approximation + U calculations with moderate values of the U parameter.

First-Principles Study of Substitutional Metal Impurities in Graphene: Structural, Electronic and Magnetic Properties. E.J.G.Santos, A.Ayuela, D.Sánchez-Portal: New Journal of Physics, 2010, 12[5], 053012