Spin Hall Effect
Spin Hall Effect
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DOI：
10.1117/12.798110
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发表时间：
2008-08
期刊：
影响因子：
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通讯作者：
Michel Dyakonov
中科院分区：
文献类型：
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作者：
Michel Dyakonov
1971年，Dyakonov和Perel预测了自旋霍尔效应和相关的输运现象，这些现象源于自旋轨道相互作用引起的电荷和自旋流的耦合[1，2]。根据[3]中的建议，圣彼得堡的约费研究所的弗勒芒小组在这一领域进行了第一次实验[4，5]，首次观察到了现在被称为逆自旋霍尔效应的现象。至于自旋霍尔效应本身，它不得不等待33年才被圣巴巴拉（美国）[6]和剑桥（英国）[7]的两个小组实验发现。这些观测引起了人们极大的兴趣，并引发了大量的实验和理论研究，发表了数百篇论文。自旋霍尔效应在于在载流导体的边界处的自旋累积，自旋的方向在相对的边界处相反。对于圆柱形导线，自旋围绕表面缠绕。边界自旋极化与电流成比例，并且当电流方向反转时改变符号。“自旋霍尔效应”一词是由赫希在1999年提出的[8]。它确实有点类似于正常的霍尔效应，其中由于磁场中的洛伦兹力的作用，相反符号的电荷在样品边界处积累。然而，存在显著差异。首先，自旋积累不需要磁场。相反，如果施加垂直于自旋方向的磁场，则会破坏自旋极化。其次，边界处的自旋极化值受到自旋弛豫的限制，并且极化存在于由自旋扩散长度决定的相对较宽的自旋层中，通常在1 μm的量级上（与在正常霍尔效应中电荷积累的小得多的德拜屏蔽长度相反）。
The Spin Hall Effect and related transport phenomena originating from the coupling of the charge and spin currents due to spin-orbit interaction were predicted in 1971 by Dyakonov and Perel [1, 2]. Following the suggestion in [3], the first experiments in this domain were done by Fleisher's group at Ioffe Institute in Saint Petersburg [4, 5], providing the first observation of what is now called the Inverse Spin Hall Effect. As to the Spin Hall Effect itself, it had to wait for 33 years before it was experimentally discovered by two groups in Santa Barbara (US) [6] and in Cambridge (UK) [7]. These observations aroused considerable interest and triggered intense research, both experimental and theoretical, with hundreds of publications. The Spin Hall Effect consists in spin accumulation at the boundaries of a current-carrying conductor, the directions of the spins being opposite at the opposing boundaries. For a cylindrical wire the spins wind around the surface. The boundary spin polarization is proportional to the current and changes sign when the direction of the current is reversed. The term "Spin Hall Effect" was introduced by Hirsch [8] in 1999. It is indeed somewhat similar to the normal Hall effect, where charges of opposite signs accumulate at the sample boundaries due to the action of the Lorentz force in magnetic field. However, there are significant differences. First, no magnetic field is needed for spin accumulation. On the contrary, if a magnetic field perpendicular to the spin direction is applied, it will destroy the spin polarization. Second, the value of the spin polarization at the boundaries is limited by spin relaxation, and the polarization exists in relatively wide spin layers determined by the spin diffusion length, typically on the order of 1 μm (as opposed to the much smaller Debye screening length where charges accumulate in the normal Hall effect).