Electric control of the spin Hall effect by intervalley transitions
Electric control of the spin Hall effect by intervalley transitions
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DOI：
10.1038/nmat4059
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发表时间：
2014-10-01
期刊：
影响因子：
41.2
通讯作者：
Barnes, C. H. W.
中科院分区：
文献类型：
--
作者：
Okamoto, N.;Kurebayashi, H.;Barnes, C. H. W.
通过电子手段控制与自旋相关的材料特性是迈向未来自旋电子技术的关键一步。自旋霍尔效应 (SHE) 对于生成、检测和使用自旋电流变得越来越重要，但其强度（以 SHE 角度量化）最终由任何给定材料系统中存在的自旋轨道耦合 (SOC) 的大小决定。然而，如果可以通过填充具有不同 SOC 特性的电子结构的不同区域（谷）来控制产生 SHE 的电子，则可以在单个样本内直接调整 SHE 角度。在这里，我们报告了在室温下通过导带中诱导的电层间跃迁对块状砷化镓中的 SHE 的操纵。自旋霍尔角是通过测量漂移通过GaAs霍尔条的光激发自旋极化电子驱动的电动势来确定的。通过控制不同（Gamma 和 L）谷中的电子数量，我们将角度从 0.0005 控制到 0.02。这种 40 倍的变化在 GaAs 中是前所未有的，达到的最高值可与重金属 Pt 相媲美。
Controlling spin-related material properties by electronic means is a key step towards future spintronic technologies. The spin Hall effect (SHE) has become increasingly important for generating, detecting and using spin currents, but its strength-quantified in terms of the SHE angle-is ultimately fixed by the magnitude of the spin-orbit coupling (SOC) present for any given material system. However, if the electrons generating the SHE can be controlled by populating different areas (valleys) of the electronic structure with different SOC characteristic the SHE angle can be tuned directly within a single sample. Here we report the manipulation of the SHE in bulk GaAs at room temperature by means of an electrical intervalley transition induced in the conduction band. The spin Hall angle was determined by measuring an electromotive force driven by photoexcited spin-polarized electrons drifting through GaAs Hall bars. By controlling electron populations in different (Gamma and L) valleys, we manipulated the angle from 0.0005 to 0.02. This change by a factor of 40 is unprecedented in GaAs and the highest value achieved is comparable to that of the heavy metal Pt.