Xue Xin, Huang Fobao, Hu Gongwei
Department of Physics, Lvliang University, Lvliang 03300, China.
School of Microelectronics, Northwestern Polytechnical University, Xi'an 710072, China.
Phys Chem Chem Phys. 2023 Oct 4;25(38):26164-26171. doi: 10.1039/d3cp02747c.
Manipulating spin polarization in wide-gap wurtzite semiconductors is crucial for the development of high-temperature spintronics applications. A topological insulator revealed recently in wurtzite quantum wells (QWs) provides a platform to mediate spin-polarized transport through the polarization field-driven topological edges and large Rashba spin-orbit coupling (SOC). Here, we propose a spin-polarized device in a quantum point contact (QPC) structure based on ZnO/CdO wurtzite topological QWs. The results show that the QPC width can sufficiently control the lateral spin-orbit coupling (SOC) as well as the band gap of the edge states through the quantum size effect. As a result, the spin-polarized conductance exhibits oscillation due to the spin precession, which can be controlled by adjusting the voltage imposed on the split gate. The QPC-induced large spin splitting is highly nonlinear and becomes strong close to the gap. The spin splitting of the edge states will be suppressed for QPC widths greater than 50 nm, and thus lead to an extremely long spin precession length. This QPC width-dependent lateral SOC effect provides an emerging electrical approach to manipulate spin-polarized electron transport in topological wurtzite systems.
在宽禁带纤锌矿半导体中操控自旋极化对于高温自旋电子学应用的发展至关重要。最近在纤锌矿量子阱（QW）中发现的拓扑绝缘体提供了一个平台，可通过极化场驱动的拓扑边缘和大的Rashba自旋轨道耦合（SOC）来介导自旋极化输运。在此，我们提出一种基于ZnO/CdO纤锌矿拓扑量子阱的量子点接触（QPC）结构中的自旋极化器件。结果表明，QPC宽度可通过量子尺寸效应充分控制横向自旋轨道耦合（SOC）以及边缘态的带隙。因此，由于自旋进动，自旋极化电导呈现振荡，这可通过调节施加在分裂栅极上的电压来控制。QPC诱导的大自旋分裂高度非线性，且在接近能隙时变强。对于宽度大于50 nm的QPC，边缘态的自旋分裂将受到抑制，从而导致极长的自旋进动长度。这种依赖于QPC宽度的横向SOC效应为操控拓扑纤锌矿系统中的自旋极化电子输运提供了一种新兴的电学方法。
