Spin-current generation from local spin polarization induced by current through local inversion asymmetry: Double quantum well structure
Spin-current generation from local spin polarization induced by current through local inversion asymmetry: Double quantum well structure
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DOI：
10.1103/physrevb.107.115306
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发表时间：
2023-03
影响因子：
3.7
通讯作者：
Yuta Suzuki;Yuma Kitagawa;S. Tezuka;H. Akera
中科院分区：
文献类型：
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作者：
Yuta Suzuki;Yuma Kitagawa;S. Tezuka;H. Akera
在没有反转对称性的系统中，电流诱导自旋极化（CISP）可以有效地产生自旋电流。本文提出了另一种方法，即从具有反平行CISP形式的反对称系统中局部产生的CISP产生自旋流。在这种方法中，局部CISP是通过子晶格和电极之间的选择性接触从子晶格中提取的。作为具有这种反平行CISP的最简单的系统，我们考虑对称双量子阱结构（DQWS），并使用Boltzmann方程在弛豫时间近似下计算与DQWS的一个阱平行接触的金属层的反平行CISP和自旋电流。当费米能量足够大，第一激发子带被占据时，自旋电流的大小与反平行CISP的大小成正比，随着阱间隧道耦合的增加而增加，并达到具有破缺反转对称性的去耦量子阱的两倍。这样的估计表明，如果反转对称性局部破缺，则反转对称系统在产生自旋流中可能是有用的。
The current-induced spin polarization (CISP) in a system without the inversion symmetry is known to efficiently generate the spin current. In this paper we propose another approach, generating the spin current from the CISP locally arising in a system with the inversion symmetry in the form of the antiparallel CISP in sublattice structure. In this approach the local CISP is extracted from one of sublattices by a selective contact between the sublattice and an electrode. As the simplest system with such antiparallel CISP, we consider a symmetric double-quantum-well structure (DQWS) and calculate the antiparallel CISP and the spin current to a metallic layer in parallel contact with one well of the DQWS using the Boltzmann equation in the relaxation time approximation. When the Fermi energy is large enough that the first-excited sub-band is occupied, the magnitude of the spin current, which is proportional to that of the antiparallel CISP, increases with the interwell tunnel coupling and reaches twice the value of the decoupled quantum well with the broken inversion symmetry. Such an estimate suggests that inversion-symmetric systems can be useful in generating the spin current if the inversion symmetry is locally broken.