Quenching of the quantum Hall effect in graphene with scrolled edges
  Edge nanoscrolls are shown to strongly influence transport properties of suspended graphene in the quantum Hall regime. The relatively long arc length of the scrolls in combination with their compact transverse size results in formation of many nonchiral transport channels in the scrolls. They short-circuit the bulk current paths and inhibit the observation of the quantized two-terminal resistance. Unlike competing theoretical proposals, this mechanism of disrupting the Hall quantization in suspended graphene is not caused by ill-chosen placement of the contacts, singular elastic strains, or a small sample size. 
Alessandro Cresti, Michael M. Fogler, Francisco Guinea, A. H. Castro   Neto and Stephan Roche
cond-mat.mes-hall