Anomalous spin–orbit torques in magnetic single-layer films
Anomalous spin–orbit torques in magnetic single-layer films
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DOI：
10.1038/s41565-019-0504-0
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发表时间：
2019-02
影响因子：
38.3
通讯作者：
Wenrui Wang;Tao Wang;V. Amin;Yangchao Wang;Anil Radhakrishnan;Angie Davidson;Shane R. Allen;T. Silva;H. Ohldag;D. Balzar;B. Zink;P. Haney;J. Xiao;D. Cahill;V. Lorenz;X. Fan
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文献类型：
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作者：
Wenrui Wang;Tao Wang;V. Amin;Yangchao Wang;Anil Radhakrishnan;Angie Davidson;Shane R. Allen;T. Silva;H. Ohldag;D. Balzar;B. Zink;P. Haney;J. Xiao;D. Cahill;V. Lorenz;X. Fan
自旋霍尔效应耦合电荷和自旋传输，–，从而实现磁化强度的电控制。自旋霍尔相关输运的一个典型例子是反常霍尔效应 (AHE)，首次在 1880 年观察到，其中垂直于磁性薄膜中磁化强度的电流在表面上产生电荷积累。在这里，我们报告了 AHE 对应物的观察结果，我们称之为反常自旋轨道扭矩（ASOT），其中与磁化平行的电流在磁性薄膜表面产生相反的自旋轨道扭矩。我们将 ASOT 解释为 Ni80Fe20 中产生的类自旋霍尔电流，其效率为 0.053±0.003，与 Pt 的自旋霍尔角相当。在其他常见的铁磁金属中也观察到类似的效应，包括钴、镍和铁。第一原理计算证实了测量值的数量级。这项工作表明，尽管自旋相移，铁磁体内仍可以产生自旋极化横向于磁化强度的强自旋电流。在研究铁磁/非磁双层中的自旋轨道扭矩时，应考虑到 ASOT 的大幅值。
The spin Hall effect couples charge and spin transport, –, enabling electrical control of magnetization,. A quintessential example of spin-Hall-related transport is the anomalous Hall effect (AHE), first observed in 1880, in which an electric current perpendicular to the magnetization in a magnetic film generates charge accumulation on the surfaces. Here, we report the observation of a counterpart of the AHE that we term the anomalous spin–orbit torque (ASOT), wherein an electric current parallel to the magnetization generates opposite spin–orbit torques on the surfaces of the magnetic film. We interpret the ASOT as being due to a spin-Hall-like current generated with an efficiency of 0.053 ± 0.003 in Ni80Fe20, comparable to the spin Hall angle of Pt. Similar effects are also observed in other common ferromagnetic metals, including Co, Ni and Fe. First-principles calculations corroborate the order of magnitude of the measured values. This work suggests that a strong spin current with spin polarization transverse to the magnetization can be generated within a ferromagnet, despite spin dephasing. The large magnitude of the ASOT should be taken into consideration when investigating spin–orbit torques in ferromagnetic/non-magnetic bilayers.