▎ 摘　　要

By employing a configuration interaction approach, we study the spin polarization induced by an electric field applied to graphene nanodots. The evolution of both the ground and excited states of the graphene nanodot with the applied electric field is calculated systematically. Three clearly separated field regimes have been identified for the spin gap in the model system, namely, (a) nearly constant in the nonmagnetic phase, (b) rapidly decreasing in the antiferromagnetic phase, and (c) exponential decay in the ferromagnetic phase. It is therefore demonstrated that ferromagnetism can be induced purely by applying an electric field to a nonmagnetic graphene nanodot. Electron-electron interactions which are greatly modified by the applied electric field are believed to account for the two consecutive magnetic phase transitions.