= Graphene exfoliation and field-effect experiments
{title2=2004–2005}
<Andre Geim>, <Konstantin Novoselov> and collaborators mechanically cleaved <graphite>, identified thin flakes, and fabricated multi-terminal <Hall bars> on oxidized <silicon>. A substrate gate changed the <carrier density>; longitudinal <electrical resistance> and the <Hall coefficient> supplied different checks. The 2004 report included one-, two- and three-layer devices and described a few-layer semimetal interpretation. Layer identification and electrical control were separate experimental achievements.<Electric Field Effect in Atomically Thin Carbon Films by Konstantin Novoselov and others>[pp.1–2 and Figs.1–2: preparation, thickness selection and electrical measurements]{ref}
The 2005 monolayer study used an <optical microscope>, <electron microscopy> and <atomic force microscopy> to select monolayers. It then measured <Shubnikov-de Haas oscillations> as <temperature>, gate voltage and <magnetic field> varied. Their damping inferred a density-dependent <cyclotron effective mass>; comparison with oscillation frequency tested a linear <dispersion relation>. A comparison with two-layer devices also distinguished their <quantum Hall effect> sequences. These are complementary tests of the monolayer model, rather than consequences of finding a thin-looking flake alone.<Two-Dimensional Gas of Massless Dirac Fermions in Graphene by Konstantin Novoselov and others>[pp.1–3, Figs.2–4: monolayer selection, oscillation damping and bilayer comparison]{ref}
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