arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1503.03456cond-mat.dis-nncond-mat.mes-hall
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拓扑绝缘体表面无序的“全息”处理

`Holographic' treatment of surface disorder on a topological insulator

Kun Woo Kim, Roger S. K. Mong, Marcel Franz, Gil Refael

摘要:

表面无序对电子系统的影响对于具有表面和边缘状态的拓扑相特别有趣。使用精确对角化,已经证明了3D拓扑绝缘体的表面态在强烈的表面无序中存活,并且简单地被推到块体的干净部分。在这里,我们探索了一种新的方法,分析消除干净的散装,并减少了$D$维问题内的$(D-1)$维无序表面的哈密顿对角化问题。这种复杂性的显着降低允许分析比精确对角化更大的系统。我们使用我们的方法来分析一个二维拓扑自旋霍尔绝缘体与非磁性和磁性边缘杂质,我们计算的概率密度(或局域态密度)的零能量本征态作为边缘平行动量和层指数的函数。我们的分析表明,达到热力学极限的行为所需的系统大小随无序度的增加而增加。我们还计算了边缘电导作为无序强度的函数,并绘制了一个下限的长度尺度标记的交叉热力学极限。

英文摘要:

The effect of surface disorder on electronic systems is particularly interesting for topological phases with surface and edge states. Using exact diagonalization, it has been demonstrated that the surface states of a 3D topological insulator survive strong surface disorder, and simply get pushed to a clean part of the bulk. Here we explore a new method which analytically eliminates the clean bulk, and reduces a $D$-dimensional problem to a Hamiltonian-diagonalization problem within the $(D-1)$-dimensional disordered surface. This dramatic reduction in complexity allows the analysis of significantly bigger systems than is possible with exact diagonalization. We use our method to analyze a 2D topological spin-Hall insulator with non-magnetic and magnetic edge impurities, and we calculate the probability density (or local density of states) of the zero-energy eigenstates as a function of edge-parallel momentum and layer index. Our analysis reveals that the system size needed to reach behavior in the thermodynamic limit increases with disorder. We also compute the edge conductance as a function of disorder strength, and chart a lower bound for the length scale marking the crossover to the thermodynamic limit.

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