Effect of random edge-vacancy disorder in zigzag graphene nanoribbons
Effect of random edge-vacancy disorder in zigzag graphene nanoribbons
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DOI：
10.1103/physrevb.94.165126
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发表时间：
2016-10
影响因子：
3.7
通讯作者：
J. Baldwin;Y. Hancock
中科院分区：
文献类型：
--
作者：
J. Baldwin;Y. Hancock
研究了具有单氢边缘钝化的小宽度锯齿形石墨烯纳米带（ZGNR）的磁性和相干传输特性作为随机边缘空位无序和带长度的函数。将具有 (i) 最近邻跳跃和 (ii) 最多第三最近邻跳跃的非相互作用紧束缚模型的结果与边缘缺陷 ZGNR 的扩展平均场 Hubbard 模型（长度 = 48.02 Å 和宽度 = 9.24 Å）获得的结果进行比较。通过系综平均，无论随机边缘空位无序的程度如何，都可以发现持久的磁性和哈伯德-U（即自旋生成）电导间隙。在较长的器件长度（高达 144.1 Å）和高无序度（42.5%）下，非相互作用模型系统中的间隙打开，而哈伯德计算的系统中的间隙变得依赖于自旋。在所有情况下，电导间隙随着系统长度的增加而增加，尽管哈伯德系统中的间隙由于对边缘无序的鲁棒性增强而保持较小。整体平均哈伯德结果中磁态的连续性和带隙鲁棒性表明动力学、无序、系统尺寸和自旋相互作用之间存在复杂的相互作用。这些发现可能有助于巩固之前使用非相互作用模型来研究 ZGNR 紊乱的研究。
The magnetic and coherent transport properties of small-width zigzag graphene nanoribbons (ZGNRs) with monohydrogen edge passivation are investigated as a function of random edge-vacancy disorder and ribbon length. Results from noninteracting tight-binding models with (i) nearest and (ii) up to third nearest neighbor hopping are compared against those obtained from an extended mean-field Hubbard model for edge-defected ZGNRs (length = 48.02 Å and width = 9.24 Å). Through ensemble averaging, a persistent magnetism and Hubbard-U (i.e., spin-generated) conductance gap is found irrespective of the extent of random edge-vacancy disorder. At longer device lengths (up to 144.1 Å) and at high disorder (42.5%), gaps open in the noninteracting model systems, whereas the gap in the Hubbard-calculated systems becomes spin dependent. In all cases, the conductance gaps increase as a function of increasing system length, although the gaps in the Hubbard systems remain smaller due to increased robustness against edge disorder. The continuance of the magnetic state and gap robustness in the ensemble-averaged Hubbard results indicates a complex interplay between the kinetics, disorder, system size, and spin interaction. Such findings may serve to reinform previous studies that have used noninteracting models to investigate disorder in ZGNRs.