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arXiv 2204.04531cond-mat.mes-hall
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无序时间反转反转对称破缺拓扑绝缘体薄膜中自旋霍尔电导的增强和稳定

Enhanced and stable spin Hall conductivity in a disordered time-reversal and inversion symmetry broken topological insulator thin film

Siamak Pooyan, Mir Vahid Hosseini

摘要:

我们考虑一个无序的拓扑绝缘体薄膜放置在一个铁磁绝缘体的顶部与一个垂直的交换场$M$和受到一个垂直的电场。铁磁绝缘体的存在导致拓扑绝缘体薄膜的底表面态变为自旋极化的,并且电场在两个表面态之间提供电势差$V$,导致系统中的时间反转和反转对称性的破坏。利用Kubo形式,采用第一玻恩近似和自洽玻恩近似,我们计算了自旋霍尔电导率。我们发现,对于小的$V$值,可以通过远离电荷中性点的大的$M$值产生大的自旋电导率。但是对于大的$V$值,即使在电荷中性点附近具有小的$M$值,也可以促进自旋电导率。顶点校正的效果和稳定性的大自旋电导率对障碍也检查。

英文摘要:

We consider a disordered topological insulator thin film placed on the top of a ferromagnetic insulator with a perpendicular exchange field $M$ and subjected to a perpendicular electric field. The presence of ferromagnetic insulator causes that bottom surface states of the topological insulator thin film become spin polarized and the electric field provides a potential difference $V$ between the two surface states, resulting in breaking of time-reversal and inversion symmetry in the system. Using Kubo formalism and employing the first Born approximation as well as the self-consistent Born approximation, we calculate the spin Hall conductivity. We find that for small values of $V$, a large spin conductivity can be generated through large values of $M$ away from the charge neutrality point. But for large values of $V$, the spin conductivity can be promoted even with small values of $M$ around the charge neutrality point. The effect of vertex corrections and the stability of the obtained large spin conductivity against disorders are also examined.

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