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arXiv 1302.5207cond-mat.mes-hallcond-mat.mtrl-sci
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在碳原子链中测量的电导率

Electrical conductivity measured in atomic carbon chains

O. Cretu, A. R. Botello-Mendez, I. Janowska, C. Pham-Huu, J. -C. Charlier, F. Banhart

摘要:

本研究首次报道了单原子碳链的电导率测量结果。这些链是通过将碳原子从石墨烯带中解开而获得的,同时电流流过石墨烯带,并依次流过链。链的形成伴随着电导率的特征性下降。碳链的电导率比以前预测的理想链要低得多。使用密度泛函和多体微扰理论的第一性原理计算表明,链中的应变以决定性的方式决定电导率。事实上,碳链总是处于变化的非零应变下,该应变将其原子结构从累积多炔构型转变为多炔构型,从而诱导可调带隙。修改后的电子结构和接触到石墨外围的特性解释了局部约束的碳链的低电导率。

英文摘要:

The first electrical conductivity measurements of monoatomic carbon chains are reported in this study. The chains were obtained by unraveling carbon atoms from graphene ribbons while an electrical current flowed through the ribbon and, successively, through the chain. The formation of the chains was accompanied by a characteristic drop in the electrical conductivity. The conductivity of carbon chains was much lower than previously predicted for ideal chains. First-principles calculations using both density functional and many-body perturbation theory show that strain in the chains determines the conductivity in a decisive way. Indeed, carbon chains are always under varying non-zero strain that transforms its atomic structure from cumulene to polyyne configuration, thus inducing a tunable band gap. The modified electronic structure and the characteristics of the contact to the graphitic periphery explain the low conductivity of the locally constrained carbon chain.

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