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arXiv 1604.07623cond-mat.dis-nn
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石墨烯中各向异性无序引起的Lévy飞行

Lévy flights due to anisotropic disorder in graphene

S. Gattenloehner, I. V. Gornyi, P. M. Ostrovsky, B. Trauzettel, A. D. Mirlin, M. Titov

摘要:

我们研究了石墨烯的输运性质,其具有各向异性分布的现场杂质(吸附原子),这些杂质随机放置在沿碳键绘制的每三条线上。我们表明,条纹状态的特点是强烈抑制背散射在这个模型中形成的方向的线。该系统揭示了Lévy-flight运输在条纹方向,使相应的电导率增加的平方根的系统长度。因此,将这种类型的无序添加到狄拉克点附近的清洁石墨烯强烈地增强了导电性,这与导致安德森局域化的现场杂质的完全随机分布形成鲜明对比。的效果都证明了使用Kwant代码的数值模拟和分析理论的基础上自洽的$T$矩阵近似。

英文摘要:

We study transport properties of graphene with anisotropically distributed on-site impurities (adatoms) that are randomly placed on every third line drawn along carbon bonds. We show that stripe states characterized by strongly suppressed back-scattering are formed in this model in the direction of the lines. The system reveals Lévy-flight transport in stripe direction such that the corresponding conductivity increases as the square root of the system length. Thus, adding this type of disorder to clean graphene near the Dirac point strongly enhances the conductivity, which is in stark contrast with a fully random distribution of on-site impurities which leads to Anderson localization. The effect is demonstrated both by numerical simulations using the Kwant code and by an analytical theory based on the self-consistent $T$-matrix approximation.

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