▎ 摘　　要

It is pointed out that due to direct couplings of electronic states, point defects on graphene are strongly correlated and cannot be treated as independent scatters. In particular, for large on-site defect potential and finite quasi-particle lifetime, we show that defects induce an impurity band with density of state characterized by the Wigner semi-circle law. By including long-range Coulomb interaction, we show that depending on quasi-particle lifetime and defect density, the impurity band may support ferromagnetism. Furthermore, the impurity band can enhance the conductivity of graphene to the order of 4e(2)/h, in agreement with experimental observations. Copyright (C) EPLA, 2009