▎ 摘　　要

We show that, in graphene with a small concentration of adatoms, the total magnetic moment mu(T) can be switched on and off by varying the Fermi energy E-F, either by applying a gate voltage or by suitable chemical doping. Our calculation is carried out using a simple tight-binding model described previously, combined with a mean-field treatment of the electron-electron interaction on the adatom. The values of E-F at which the moment is turned on or off are controlled by the strength of the hopping between the graphene sheet and the adatom, the on-site energy of the adatom, and the strength of the electron-electron correlation energy U. Our result is qualitatively consistent with recent experiments [R. R. Nair et al., Nat. Commun. 4, 2010 (2013)]. (C) 2014 AIP Publishing LLC.