Spin Hall effects
Spin Hall effects
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DOI：
10.1103/revmodphys.87.1213
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发表时间：
2015-10-27
影响因子：
44.1
通讯作者：
Jungwirth, T.
中科院分区：
文献类型：
--
作者：
Sinova, Jairo;Valenzuela, Sergio O.;Jungwirth, T.
自旋霍尔效应是一种相对论性自旋轨道耦合现象的集合，其中电流可以产生横向自旋电流，反之亦然。尽管在十年前才被观察到，这些效应已经在自旋电子学中无处不在，作为标准的自旋电流发生器和探测器。本文综述了建立自旋电子学这一分支领域的理论和实验结果。我们关注的是聚合的结果，这些结果给了我们当前对这些现象的理解，这些现象已经从对自旋电流及其相关自旋积累的定性测量演变为更定量的测量。在实验框架内，基于光学、输运和磁化动力学的测量被回顾，并与效应的现象学和微观理论联系起来。在理论框架内，回顾了外在和内在机制的基本机制，并将其与铁磁体中异常霍尔效应密切相关的现象中的机制联系起来。还回顾了与基于适用于某些情况的自旋扩散方程的现象学处理的联系，以及自旋霍尔角的许多测量中使用的自旋产生的自旋泵理论。给出了产生自旋电流的自旋霍尔效应与逆自旋电流效应的进一步联系，其中电流引起非平衡自旋极化。这种效应通常伴随着自旋霍尔效应，因为它们具有共同的微观起源。当存在于由铁磁层和非磁层组成的结构中时，两者都可以通过感应电流驱动的自旋力矩或感应电压表现出相同的对称性。虽然对自旋霍尔效应场的演变和一些早期争议的解决给出了一个简短的时间顺序概述，但这篇综述的主体是从教学的角度出发的，重点是建立和接受的物理学。在这样一个年轻的领域，仍有许多有待理解和探索的地方，因此，本文概述了自旋电子学这个快速发展的领域未来的一些挑战和机遇。
Spin Hall effects are a collection of relativistic spin-orbit coupling phenomena in which electrical currents can generate transverse spin currents and vice versa. Despite being observed only a decade ago, these effects are already ubiquitous within spintronics, as standard spin-current generators and detectors. Here the theoretical and experimental results that have established this subfield of spintronics are reviewed. The focus is on the results that have converged to give us the current understanding of the phenomena, which has evolved from a qualitative to a more quantitative measurement of spin currents and their associated spin accumulation. Within the experimental framework, optical-, transport-, and magnetization-dynamics-based measurements are reviewed and linked to both phenomenological and microscopic theories of the effect. Within the theoretical framework, the basic mechanisms in both the extrinsic and intrinsic regimes are reviewed, which are linked to the mechanisms present in their closely related phenomenon in ferromagnets, the anomalous Hall effect. Also reviewed is the connection to the phenomenological treatment based on spin-diffusion equations applicable to certain regimes, as well as the spin-pumping theory of spin generation used in many measurements of the spin Hall angle. A further connection to the spin-current-generating spin Hall effect to the inverse spin galvanic effect is given, in which an electrical current induces a nonequilibrium spin polarization. This effect often accompanies the spin Hall effect since they share common microscopic origins. Both can exhibit the same symmetries when present in structures comprising ferromagnetic and nonmagnetic layers through their induced current-driven spin torques or induced voltages. Although a short chronological overview of the evolution of the spin Hall effect field and the resolution of some early controversies is given, the main body of this review is structured from a pedagogical point of view, focusing on well-established and accepted physics. In such a young field, there remains much to be understood and explored, hence some of the future challenges and opportunities of this rapidly evolving area of spintronics are outlined.