Volume 88, Number 6, December 2009
Article Number 68005
Number of page(s) 6
Section Interdisciplinary Physics and Related Areas of Science and Technology
Published online 01 December 2009
EPL, 88 (2009) 68005
DOI: 10.1209/0295-5075/88/68005

Resonant impurity band induced by point defects in graphene

Bor-Luen Huang1 and Chung-Yu Mou1, 2

1   Department of Physics, National Tsing Hua University - Hsinchu 30043, Taiwan
2   Physics Division, National Center for Theoretical Sciences - P.O.Box 2-131, Hsinchu, Taiwan

received 10 July 2009; accepted in final form 24 November 2009; published December 2009
published online 24 December 2009

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 4e2/h, in agreement with experimental observations.

81.05.Uw - Carbon, diamond, graphite.
61.72.J- - Point defects and defect clusters.
75.75.-c - Magnetic properties of nanostructures.

© EPLA 2009