Two different points of view are available to understand the behavior of graphene at low energies. One is considering a large NF that makes graphene a semimetal, and another for small NF<2.5 that would make graphene a narrow gap semiconductor (D. T. Son, Phys. rev. B 75, 235423 (2007)), a prediction supported independently by Monte Carlo simulations (J. E. Drut and T. A. L\"ahde, Phys. Rev. Lett. 102, 026802 (2009), see also Phys. Rev. B 79, 241405(R) (2009)). Taking into account recently obtained experimental evidence for weakly coupled graphene layers, i.e. graphite (N. Garc\'ia et al., arXiv/1106.0437), we tend to support the last one.
@article{arxiv.1110.2601,
title = {Comment on "Dirac cones reshaped by interaction effects in suspended graphene" by Elias et al., Nature Physics 7, 701 (2011)},
author = {N. García and P. Esquinazi and A. A. Pasa},
journal= {arXiv preprint arXiv:1110.2601},
year = {2011}
}