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arXiv 1111.6639cond-mat.dis-nncond-mat.mes-hall
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三维磁无序拓扑绝缘体表面局域态密度的多重分形性质

Multifractal nature of the surface local density of states in three-dimensional topological insulators with magnetic and nonmagnetic disorder

Matthew S. Foster

摘要:

本文计算了二维空间中单个狄拉克费米子由于弱淬火无序引起的局域态密度涨落的多重分形谱。我们的结果与Z_2拓扑绝缘体如Bi_2Se_3和Bi_2Te_3的表面有关,在那里LDOS调制可以通过扫描隧道显微镜直接探测。我们发现一个定性的差异,在光谱中获得的磁性与非磁性的障碍。随机极化的磁性杂质诱导二次多重分形在一阶的杂质密度,相比之下,没有运营商表现出多重分形标度在这个顺序的非磁性杂质配置文件。对于时间反演不变的情况下,我们计算第一个非平凡的多重分形校正,它出现在两个循环(杂质密度平方)。我们讨论了光谱增强的狄拉克点,由于重整化,我们调查已知的结果强无序的相反的限制。

英文摘要:

We compute the multifractal spectra associated to local density of states (LDOS) fluctuations due to weak quenched disorder, for a single Dirac fermion in two spatial dimensions. Our results are relevant to the surfaces of Z_2 topological insulators such as Bi_2Se_3 and Bi_2Te_3, where LDOS modulations can be directly probed via scanning tunneling microscopy. We find a qualitative difference in spectra obtained for magnetic versus non-magnetic disorder. Randomly polarized magnetic impurities induce quadratic multifractality at first order in the impurity density; by contrast, no operator exhibits multifractal scaling at this order for a non-magnetic impurity profile. For the time-reversal invariant case, we compute the first non-trivial multifractal correction, which appears at two loops (impurity density squared). We discuss spectral enhancement approaching the Dirac point due to renormalization, and we survey known results for the opposite limit of strong disorder.

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