Department of Electrical Engineering and Center for Solid State Electronics Research, Arizona State University, Tempe, AZ 85287-5706, USA.
J Phys Condens Matter. 2011 Nov 23;23(46):465301. doi: 10.1088/0953-8984/23/46/464203. Epub 2011 Nov 3.
We use numerical simulations to investigate the spin Hall effect in quantum wires in the presence of both Rashba and Dresselhaus spin-orbit coupling. We find that the intrinsic spin Hall effect is highly anisotropic with respect to the orientation of the wire, and that the nature of this anisotropy depends strongly on the electron density and the relative strengths of the Rashba and Dresselhaus spin-orbit couplings. In particular, at low densities, when only one subband of the quantum wire is occupied, the spin Hall effect is strongest for electron momentum along the [N110] axis, which is the opposite of what is expected for the purely 2D case. In addition, when more than one subband is occupied, the strength and anisotropy of the spin Hall effect can vary greatly over relatively small changes in electron density, which makes it difficult to predict which wire orientation will maximize the strength of the spin Hall effect. These results help to illuminate the role of quantum confinement in spin-orbit-coupled systems, and can serve as a guide for future experimental work on the use of quantum wires for spin-Hall-based spintronic applications.
我们使用数值模拟研究了在同时存在 Rashba 和 Dresselhaus 自旋轨道耦合的量子线中的自旋霍尔效应。我们发现，自旋霍尔效应对于线的取向具有高度各向异性，并且这种各向异性的性质强烈依赖于电子密度和 Rashba 和 Dresselhaus 自旋轨道耦合的相对强度。特别是，在低密度下，当量子线的只有一个子带被占据时，自旋霍尔效应在电子动量沿着[N110]轴的方向上最强，这与纯粹的 2D 情况预期的相反。此外，当占据多个子带时，自旋霍尔效应的强度和各向异性可以在电子密度相对较小的变化下发生很大变化，这使得很难预测哪种线取向将最大化自旋霍尔效应的强度。这些结果有助于阐明量子限制在自旋轨道耦合系统中的作用，并可作为未来基于量子线的自旋霍尔自旋电子应用实验工作的指南。
