Large-scale mesoscopic transport in nanostructured graphene

Anderson localization is one of the most important physical phenomena caused by the wave nature of quantum particles. It was originally proposed for the electronic system，but never clearly observed because the wave nature of electrons is usually only manifest at extremely small distances，denoted the dephasing length，and therefore making the observation very difficult. In this article we report the first observation of Anderson localization in 2 dimensions，on nanostructured graphene. Perhaps more important is the fact that we have discovered a way to enhance the dephasing length of electrons，by at least one order of magnitude，so that the electron phase may now be more easily manipulated. In this article，we use exponential sample-size scaling of conductance to demonstrate strong electron localization in three sets of nanostructured antidot graphene samples with localization lengths of 1.1，2.0，and 3.4 μm. The localization length is observed to increase with applied magnetic field，in accurate agreement with the theoretical prediction. The large-scale mesoscopic transport is manifest as a parallel conduction channel to 2D variable range hopping，with a Coulomb quasigap around the Fermi level. The opening of the correlation quasigap，observable below 25 K through the temperature dependence of conductance，makes possible the exponential suppression of inelastic scatterings and thereby leads to an observed dephasing length of 10 μm.