Enhanced weak localization effect in few-layer graphene.

We have investigated the weak localization correction to magnetoresistance in one to six layer graphene structures. The magnetoresistance measurements have revealed that, in addition to the known transition from weak anti-localization in monolayer graphene to weak localization in bilayer graphene, the weak localization effect becomes more pronounced as the number of graphene layers increases. The obtained results substantiate that because few-layer graphene suppresses mesoscopic corrugations and increases intervalley scattering it leads to the observed enhancement of negative resistance, resulting in the restoration of the weak localization in graphene materials. High field magnetoresistance measurements show non-linear behavior, which indicates the breaking of sub-lattice symmetry and the formation of excitonic gap in the Landau level.