Dissipative Quantum Hall Effect in Graphene near the Dirac Point

We report on the unusual nature of the ν=0 state in the integer quantum Hall effect (QHE) in graphene and show that electron transport in this regime is dominated by counterpropagating edge states. Such states, intrinsic to massless Dirac quasiparticles, manifest themselves in a large longitudinal resistivity ρ_xx≳h/e², in striking contrast to ρ_xx behavior in the standard QHE. The ν=0 state in graphene is also predicted to exhibit pronounced fluctuations in ρ_xy and ρ_xx and a smeared zero Hall plateau in σ_xy, in agreement with experiment. The existence of gapless edge states puts stringent constraints on possible theoretical models of the ν=0 state.