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Density dependent electrical conductivity in suspended graphene: Approaching the Dirac point in transport

We theoretically consider, comparing with the existing experimental literature, the electrical conductivity of gated monolayer graphene as a function of carrier density, temperature, and disorder in order to assess the prospects of accessing the Dirac point using transport studies in high-quality suspended graphene. We show that the temperature dependence of graphene conductivity around the charge neutrality point provides information about how close the system can approach the Dirac point although competition between long-range and short-range disorder as well as between diffusive and ballistic transport may considerably complicate the picture. We also find that acoustic phonon scattering contribution to the graphene resistivity is always relevant at the Dirac point in contrast to higher density situations where the acoustic phonon contribution to the resistivity is strongly suppressed at the low temperature Bloch-Grüneisen regime. We provide detailed numerical results for temperature and density dependent conductivity for suspended graphene.