Impact of graphene quantum capacitance on transport spectroscopy

Abstract

We demonstrate experimentally that graphene quantum capacitance ${C}_{\mathrm{q}}$ can have a strong impact on transport spectroscopy through the interplay with nearby charge reservoirs. The effect is elucidated in a field-effect-gated epitaxial graphene device, in which interface states serve as charge reservoirs. The Fermi-level dependence of ${C}_{\mathrm{q}}$ is manifested as an unusual parabolic gate voltage (${V}_{\mathrm{g}}$) dependence of the carrier density, centered on the Dirac point. Consequently, in high magnetic fields $B$, the spectroscopy of longitudinal resistance (${R}_{xx}$) vs ${V}_{\mathrm{g}}$ represents the structure of the unequally spaced relativistic graphene Landau levels (LLs). ${R}_{xx}$ mapping vs ${V}_{\mathrm{g}}$ and $B$ thus reveals the vital role of the zero-energy LL on the development of the anomalously wide $\ensuremath{\nu}=2$ quantum Hall state.

Locations

• arXiv (Cornell University) - View - PDF
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• Physical Review B - View