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arXiv · 1206.3848

How close can one approach the Dirac point in graphene experimentally?

Alexander S. Mayorov·Daniel C. Elias·Ivan S. Mukhin·Sergey V. Morozov·Leonid A. Ponomarenko·Kostya S. Novoselov·A. K. Geim·Roman V. Gorbachev
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Abstract

The above question is frequently asked by theorists who are interested in graphene as a model system, especially in context of relativistic quantum physics. We offer an experimental answer by describing electron transport in suspended devices with carrier mobilities of several 10^6 cm^2V^-1s^-1 and with the onset of Landau quantization occurring in fields below 5 mT. The observed charge inhomogeneity is as low as \approx10^8 cm^-2, allowing a neutral state with a few charge carriers per entire micron-scale device. Above liquid helium temperatures, the electronic properties of such devices are intrinsic, being governed by thermal excitations only. This yields that the Dirac point can be approached within 1 meV, a limit currently set by the remaining charge inhomogeneity. No sign of an insulating state is observed down to 1 K, which establishes the upper limit on a possible bandgap.

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Alexander S. Mayorov, Daniel C. Elias, Ivan S. Mukhin, Sergey V. Morozov, Leonid A. Ponomarenko, Kostya S. Novoselov, A. K. Geim, Roman V. Gorbachev. 2012-09-03. How close can one approach the Dirac point in graphene experimentally?. https://doi.org/10.1021/nl301922d

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