Spin-momentum locking, a key property of the surface states of three-dimensional topological insulators (3DTIs), provides a new avenue for spintronics applications. One consequence of spin-momentum locking is the induction of surface spin accumulations due to applied electric fields. In this paper, we investigate the extraction of such electrically induced spins from their host TI material into adjoining conventional, hence topologically trivial, materials that are commonly used in electronics devices. We focus on effective Hamiltonians for bismuth-based 3DTI materials in the ${\mathrm{Bi}}_2{\mathrm{Se}}_3$ family, and numerically explore the geometries for extracting current-induced spins from a TI surface. In particular, we consider a device geometry in which a side pocket is attached to various faces of a 3DTI quantum wire and show that it is possible to create current-induced spin accumulations in these topologically trivial side pockets. We further study how such spin extraction depends on geometry and material parameters, and find that electron-hole degrees of freedom can be utilized to control the polarization of the extracted spins by an applied gate voltage.

中文翻译：

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从拓扑绝缘体表面进行栅极控制的自旋提取

自旋动量锁定是三维拓扑绝缘体（3DTI）表面状态的关键属性，为自旋电子学应用提供了新途径。自旋动量锁定的结果之一是由于施加电场而引起表面自旋积累。在本文中，我们研究了将这种电感应自旋从其宿主TI材料中提取到电子设备中常用的常规（因此在拓扑上是微不足道的）材料中的方法。我们重点研究了基于铋的3DTI材料的有效哈密顿量。${双}_2{硒}_3$家族，并从数字上探索从TI表面提取电流感应自旋的几何形状。尤其是，我们考虑了一种器件几何结构，其中侧袋连接到3DTI量子线的各个面上，并且表明可以在这些拓扑琐碎的侧袋中创建电流感应的自旋累积。我们进一步研究了这种自旋提取如何取决于几何形状和材料参数，并且发现可以利用施加的栅极电压来利用电子-空穴自由度来控制所提取的自旋的极化。