arXiv 0705.15402007-05cond-mat.mes-hall

石墨烯输运的自洽理论

A self-consistent theory for graphene transport

Shaffique Adam, E. H. Hwang, Victor Galitski, S. Das Sarma

备注：: To be published in Proc. Natl. Acad. Sci. USA
发表信息：: Proc. Natl. Acad. Sci. USA 104, 18392 (2007)
DOI：: 10.1073/pnas.0704772104

摘要：

我们从理论上证明了石墨烯片在零磁场下的大部分输运性质可以用带电杂质的散射来解释。我们发现，与通常的看法相反，这些属性是不普遍的，但取决于带电杂质$n_{\rm imp}$的浓度。对于脏样品（$250 \times 10^{10} {\rm cm}^{-2} < n_{\rm imp} < 400 \times 10^{10} {\rm cm}^{-2}$），在低载流子密度下的最小电导率值确实是$4 e^2/h$，与早期实验一致，对杂质浓度的依赖性较弱。对于更清洁的样品，我们预测，最小电导率强烈依赖于$n_{\rm imp}$，增加到$8 e^2/h$为$n_{\rm imp} \sim 20 \times 10^{10}{\rm cm}^{-2}$。提高石墨烯迁移率的一个明确策略是消除带电杂质或使用具有更大介电常数的衬底。

英文摘要：

We demonstrate theoretically that most of the observed transport properties of graphene sheets at zero magnetic field can be explained by scattering from charged impurities. We find that, contrary to common perception, these properties are not universal but depend on the concentration of charged impurities $n_{\rm imp}$. For dirty samples ($250 \times 10^{10} {\rm cm}^{-2} < n_{\rm imp} < 400 \times 10^{10} {\rm cm}^{-2}$), the value of the minimum conductivity at low carrier density is indeed $4 e^2/h$ in agreement with early experiments, with weak dependence on impurity concentration. For cleaner samples, we predict that the minimum conductivity depends strongly on $n_{\rm imp}$, increasing to $8 e^2/h$ for $n_{\rm imp} \sim 20 \times 10^{10}{\rm cm}^{-2}$. A clear strategy to improve graphene mobility is to eliminate charged impurities or use a substrate with a larger dielectric constant.

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英文摘要：

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