Magnetoresistance in graphene under quantum limit regime

We report the magnetoresistance (MR) in single-layer graphene field-effect transistors at different gate voltages. At low temperatures, the MR exhibits fluctuations at Dirac point, which is attributed to quantum interference effect. Apart from the Dirac point, the MR shows a linear behavior under the extreme quantum limit that is identified by Shubnikov-de Haas oscillations and quantum Hall effect. Our experimental results give a clear manifestation of the quantum linear MR.