Quantum criticality and minimal conductivity in graphene with long-range disorder.

@article{Ostrovsky2007QuantumCA,
title={Quantum criticality and minimal conductivity in graphene with long-range disorder.},
author={P. M. Ostrovsky and I. Gornyi and A. Mirlin},
journal={Physical review letters},
year={2007},
volume={98 25},
pages={
256801
}
}

We consider the conductivity sigma of graphene with negligible intervalley scattering at half filling. We derive the effective field theory, which, for the case of a potential disorder, is a symplectic-class sigma model including a topological term with theta=pi. As a consequence, the system is at a quantum critical point with a universal value of the conductivity of the order of e(2)/h. When the effective time-reversal symmetry is broken, the symmetry class becomes unitary, and sigma acquires… CONTINUE READING