Spin-orbit torques in high-resistivity-W/CoFeB/MgO
Spin-orbit torques in high-resistivity-W/CoFeB/MgO
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DOI：
10.1063/1.5027855
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发表时间：
2018-05
影响因子：
4
通讯作者：
Y. Takeuchi;Chaoliang Zhang;A. Okada;Hideo Sato;S. Fukami;H. Ohno
中科院分区：
文献类型：
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作者：
Y. Takeuchi;Chaoliang Zhang;A. Okada;Hideo Sato;S. Fukami;H. Ohno
通过溅射制备由高电阻率 (238 ± 5 µΩ cm)-W/CoFeB/MgO 组成的磁性异质结构，并通过扩展谐波测量将其自旋轨道扭矩评估为 W 厚度的函数。具有类 Slonczewski 对称性的自旋轨道扭矩的 W 厚度依赖性可以通过漂移扩散模型很好地描述，其效率参数（即所谓的有效自旋霍尔角）为 -0.62 ± 0.03。相比之下，类场自旋轨道扭矩比类 Slonczewski 扭矩小一个数量级，并且对 W 厚度没有明显的依赖性，这表明与类 Slonczewski 扭矩的起源不同。结果表明，高电阻率 W 有望用于低电流且可靠的自旋轨道扭矩控制器件。
Magnetic heterostructures consisting of high-resistivity (238 ± 5 µΩ cm)-W/CoFeB/MgO are prepared by sputtering and their spin-orbit torques are evaluated as a function of W thickness through an extended harmonic measurement. W thickness dependence of the spin-orbit torque with the Slonczewski-like symmetry is well described by the drift-diffusion model with an efficiency parameter, the so-called effective spin Hall angle, of −0.62 ± 0.03. In contrast, the field-like spin-orbit torque is one order of magnitude smaller than the Slonczewski-like torque and shows no appreciable dependence on the W thickness, suggesting a different origin from the Slonczewski-like torque. The results indicate that high-resistivity W is promising for low-current and reliable spin-orbit torque-controlled devices.