Disorder induced magnetoresistance in a two dimensional electron system
  We predict and demonstrate that a disorder induced carrier density inhomogeneity causes magnetoresistance (MR) in a two-dimensional electron system. Our experiments on graphene show a quadratic MR persisting far from the charge neutrality point. Effective medium calculations show that for charged impurity disorder, the low-field MR is a universal function of the ratio of carrier density to fluctuations in carrier density, a power-law when this ratio is large, in excellent agreement with experiment. The MR is generic and should occur in other materials with large carrier density inhomogeneity. 
Jinglei Ping and Indra Yudhistira and Navneeth Ramakrishnan and   Sungjae Cho and Shaffique Adam and Michael S. Fuhrer
cond-mat.mes-hall