Volume 79, Number 5, September 2007
Article Number 57003
Number of page(s) 5
Section Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties
Published online 30 July 2007
EPL, 79 (2007) 57003
DOI: 10.1209/0295-5075/79/57003

Anomalously large conductance fluctuations in weakly disordered graphene

A. Rycerz1, J. Tworzydlo2 and C. W. J. Beenakker3

1  Marian Smoluchowski Institute of Physics, Jagiellonian University - Reymonta 4, 30059 Kraków, Poland
2  Institute of Theoretical Physics, Warsaw University - Hoza 69, 00681 Warsaw, Poland
3  Instituut-Lorentz, Universiteit Leiden - P.O. Box 9506, 2300 RA Leiden, The Netherlands

received 29 March 2007; accepted in final form 6 July 2007; published September 2007
published online 30 July 2007

We have studied numerically the mesoscopic fluctuations of the conductance of a graphene strip (width W larger than length L), in an ensemble of samples with different realizations of the random electrostatic potential landscape. For strong disorder (potential fluctuations comparable to the hopping energy), the variance of the conductance approximates the value predicted by the Altshuler-Lee-Stone theory of universal conductance fluctuations, ${\rm Var}\,G_{{\rm UCF}}=0.12\,(W/L)(2e^{2}/h)^{2}$. For weaker disorder the variance is greatly enhanced if the potential is smooth on the scale of the atomic separation. There is no enhancement if the potential varies on the atomic scale, indicating that the absence of backscattering on the honeycomb lattice is at the origin of the anomalously large fluctuations.

73.23.-b - Electronic transport in mesoscopic systems.
73.20.Fz - Weak or Anderson localization.
73.40.-c - Electronic transport in interface structures.

© Europhysics Letters Association 2007