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arXiv 1402.1502cond-mat.mes-hall
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石墨烯纳米带中的空间电流模式、失相和电流成像

Spatial Current Patterns, Dephasing and Current Imaging in Graphene Nanoribbons

Joel Mabillard, Tankut Can, Dirk K. Morr

摘要:

利用非平衡Keldysh格林函数方法,研究了石墨烯纳米带中的局域非平衡电荷输运。特别是,我们证明了与离散传输共振相关的空间电流模式敏感地依赖于GNRs的几何形状,大小和纵横比,位置和数量的引线,以及存在的失相。我们确定的电流模式的空间形式之间的关系,和参与电荷传输的简并能态的数量。此外,我们证明了叠加原理的电导和空间电流模式在多引线配置。我们证明,扫描隧道显微镜(STM)可以用来成像空间电流路径GNR原子分辨率,提供重要的洞察局部电荷输运的形式。最后,我们研究了退相对空间电流图案的影响,并表明随着退相时间的减少,电流图案从弹道量子网络平滑地演变为经典电阻网络。

英文摘要:

Using the non-equilibrium Keldysh Green's function formalism, we investigate the local, non-equilibrium charge transport in graphene nanoribbons (GNRs). In particular, we demonstrate that the spatial current patterns associated with discrete transmission resonances sensitively depend on the GNRs' geometry, size, and aspect ratio, the location and number of leads, and the presence of dephasing. We identify a relation between the spatial form of the current patterns, and the number of degenerate energy states participating in the charge transport. Furthermore, we demonstrate a principle of superposition for the conductance and spatial current patterns in multiple-lead configurations. We demonstrate that scanning tunneling microscopy (STM) can be employed to image spatial current paths in GNR with atomic resolution, providing important insight into the form of local charge transport. Finally, we investigate the effects of dephasing on the spatial current patterns, and show that with decreasing dephasing time, the current patterns evolve smoothly from those of a ballistic quantum network to those of classical resistor network.

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