Structure and Electron Transport in Irradiated Monolayer Graphene

Disordered graphene has attracted the attention of many researchers. Mainly, this is due to the possibility of obtaining a high-resistance state of graphene films, which is of interest for application in electronics. This chapter discusses ion bombardment as a way of gradually inducing disorder in monolayer graphene. In variable-range-hopping (VRH), only localized states within an optimal energy band near the Fermi level are involved in the hopping process. This strong anisotropy indicates unambiguously different mechanisms of magnetoresistance (MR): negative MR in perpendicular fields is connected with orbital effects, while positive MR in parallel fields is determined by the spin polarization. As a result of averaging over different configurations, the contribution of the scattering sites to the total hopping probability vanishes due to destructive interference. The perpendicular magnetic field suppresses the interference, which leads to an increase of the hopping probability and, therefore, to the negative MR.