Enhanced conductivity in graphene layers and at their edges

We have observed that the conductivity of graphene sheets is higher whenever they are loosely bound to the underlying bulk graphite. We also observe that certain edges of the graphene layers show sharp rise in current when biased, indicating enhanced electronic density of states spatially localized near those edges. In certain edges, we do not observe this phenomenon. These two observations, i.e., enhancement of conductivity of loosely bound layers and sharp rise in current at the edges are discussed with possible reasons and invoking recent theoretical predictions. (c) 2006 American Institute of Physics.