ABSTRACT
A brief survey is provided to discuss the transport properties of graphene in the absence of an external magnetic eld. Electronic properties of mono-and bilayer graphene are strongly related to the existence of a quasiparticle spectrum, which consists of two bands that touch each other at two Dirac nodes. This structure is associated with a number of interesting features, such as Klein tunneling and electron-hole pair creation. This leads to robust transport properties, including a minimal conductivity and a constant optical conductivity, clearly indicating a deviation from conventional Drudetype transport. Moreover, recent experimental studies have revealed that the sublattice symmetry of the honeycomb lattice can be broken by chemical doping or by external gates in the case of bilayers. The broken symmetry opens a random gap in the quasiparticle spectrum which may lead to an insulating behavior. We discuss diffusion in graphene, which implies a characteristic metallic behavior in mono-and bilayer graphene, and the alternate current conductivity. The properties of the latter deviate substantially from that of a conventional metal. The behavior of plasmons in graphene, on the other hand, is similar to that of plasmons in a conventional twodimensional electron gas.
