arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1012.3575cond-mat.mes-hall
收藏

量子线中的自旋弛豫

Spin Relaxation in Quantum Wires

Paul Wenk, Stefan Kettemann

摘要:

综述了自旋轨道耦合量子线中巡游电子的自旋动力学和自旋弛豫。介绍了自旋动力学,并回顾了半导体中的自旋轨道耦合机制。自旋扩散方程的自旋轨道耦合推导,只使用直观的,经典的随机行走参数。我们给出了一个概述所有的自旋弛豫机制,特别强调在无序导体的运动窄化机制,D 'yakonov-Perel'-Spin弛豫。在这里,我们讨论特别是,存在持久的自旋螺旋解决方案的自旋扩散方程,自旋弛豫率为零。然后,我们推导出的自旋扩散方程的量子线的解决方案,并表明,有一个有效的自旋轨道场的线的宽度小于自旋进动长度$L_{\rm SO}$。我们表明,由此产生的自旋弛豫率的减少导致的量子校正的电导率的符号的变化。最后,我们提出了最近的实验结果,证实了减少的自旋弛豫率在电线的宽度小于$L_{\rm SO}$:自旋弛豫率的直接光学测量,以及运输测量,这表明从弱反本地化弱本地化的线宽度减少的尺寸交叉。开放的问题仍然存在,特别是在较窄的弹道导线,光学和运输测量似乎发现相反的行为的自旋弛豫率:增强,抑制,分别。最后,我们回顾这些和其他开放的问题,仍然挑战的理论理解和建模的实验结果。

英文摘要:

The spin dynamics and spin relaxation of itinerant electrons in quantum wires with spin-orbit coupling is reviewed. We give an introduction to spin dynamics, and review spin-orbit coupling mechanisms in semiconductors. The spin diffusion equation with spin-orbit coupling is derived, using only intuitive, classical random walk arguments. We give an overview of all spin relaxation mechanisms, with particular emphasis on the motional narrowing mechanism in disordered conductors, the D'yakonov-Perel'-Spin relaxation. Here, we discuss in particular, the existence of persistent spin helix solutions of the spin diffusion equation, with vanishing spin relaxation rates. We then, derive solutions of the spin diffusion equation in quantum wires, and show that there is an effective alignment of the spin-orbit field in wires whose width is smaller than the spin precession length $L_{\rm SO}$. We show that the resulting reduction in the spin relaxation rate results in a change in the sign of the quantum corrections to the conductivity. Finally, we present recent experimental results which confirm the decrease of the spin relaxation rate in wires whose width is smaller than $L_{\rm SO}$: the direct optical measurement of the spin relaxation rate, as well as transport measurements, which show a dimensional crossover from weak antilocalization to weak localization as the wire width is reduced. Open problems remain, in particular in narrower, ballistic wires, were optical and transport measurements seem to find opposite behavior of the spin relaxation rate: enhancement, suppression, respectively. We conclude with a review of these and other open problems which still challenge the theoretical understanding and modeling of the experimental results.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑