Abstract
We numerically calculate the conductivity of an undoped graphene sheet (size ) in the limit of a vanishingly small lattice constant. We demonstrate one-parameter scaling for random impurity scattering and determine the scaling function . Contrary to a recent prediction, the scaling flow has no fixed point () for conductivities up to and beyond the symplectic metal-insulator transition. Instead, the data support an alternative scaling flow for which the conductivity at the Dirac point increases logarithmically with sample size in the absence of intervalley scattering—without reaching a scale-invariant limit.
- Received 7 May 2007
DOI:https://doi.org/10.1103/PhysRevLett.99.106801
©2007 American Physical Society