Disorder-controlled linear magnetoresistance in monolayer graphene

Abstract

The nonsaturating linear magnetoresistance (MR) in graphene has been found for more than ten years, but its origin still lacks a quantitative study. Here, we report magneto-transport properties of monolayer graphene samples grown on silicon carbide. A positive parabolic MR is observed at low magnetic fields, and it is transformed into a large linear MR with increasing field. The observed linear MR is gradually suppressed either by increasing temperature or by increasing annealing time. The slope of the linear MR is proportional to the Hall mobility, and the crossover field, representing a transition from quadratic to linear field dependence, is proportional to the inverse of the Hall mobility. We therefore attribute the linear MR to a classical origin. This classical MR is considered to be controlled by the interaction between carrier and the low-mobility island, and the fraction of the low-mobility island is extracted. The extracted fraction is consistent with the calculated results when the absorbed acceptor is regarded as the main source of the disorder. Our data also can be explained by the effective-medium theory.