Figure 1: Quantum Hall effect in ultra-low carrier density epitaxial graphene.
From: Giant quantum Hall plateaus generated by charge transfer in epitaxial graphene
(a) Continuous field measurements of the quantum Hall effect at 2 K using a constant measurement current of 1 μA in an epitaxial graphene on SiC sample with the zero field carrier density reduced to 1.5 × 1010 cm2 by corona discharge at room temperature. Inset: an expanded plot of Rxx towards the end of the plateau. (b) I − Vxx traces indicating the onset of the quantum Hall breakdown for the high magnetic field side of the plateau and inset, for the low field side. (c) Theoretical dependence of the breakdown current for the ν = 2 quantum Hall plateau using equations (1) and (6) with B0 = 0.3 T and Bc = 2.0 T. A set of dependences are shown with the power, p, chosen as 5, 10, 15, and 20. The traditional triangular dependence of breakdown current on magnetic field for constant n becomes stretched and asymmetric as the carrier density tends towards an almost linear dependence on magnetic field. The inset shows the corresponding field dependent carrier densities. (d) Magnetic field dependence of the breakdown current (purple triangles) for the ν = 2 plateau and a best fit (solid line) using equations (1) and (6) with the power p = 13. The inset shows the corresponding magnetic field dependent carrier density.
