How Close Can One Approach the Dirac Point in Graphene Experimentally?

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• 作者：Alexander S. Mayorov ; Daniel C. Elias ; Ivan S. Mukhin ; Sergey V. Morozov ; Leonid A. Ponomarenko ; Kostya S. Novoselov ; A. K. Geim ; Roman V. Gorbachev
• 刊名：Nano Letters
• 出版年：2012
• 出版时间：September 12, 2012
• 年：2012
• 卷：12
• 期：9
• 页码：4629-4634
• 全文大小：274K
• 年卷期：v.12,no.9(September 12, 2012)
• ISSN：1530-6992

文摘

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 10⁶ cm² V^鈥? s^鈥? and with the onset of Landau quantization occurring in fields below 5 mT. The observed charge inhomogeneity is as low as 鈮?0⁸ cm^鈥?, allowing a neutral state with a few charge carriers per entire micrometer-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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