Resonant Measurement of Nonreorientable Spin-Orbit Torque from a Ferromagnetic Source Layer Accounting for Dynamic Spin Pumping
Resonant Measurement of Nonreorientable Spin-Orbit Torque from a Ferromagnetic Source Layer Accounting for Dynamic Spin Pumping
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DOI：
10.1103/physrevapplied.16.024035
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发表时间：
2021-06
影响因子：
4.6
通讯作者：
Joseph A. Mittelstaedt;D. Ralph
中科院分区：
文献类型：
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作者：
Joseph A. Mittelstaedt;D. Ralph
使用多层结构包含（钴探测器层）/（铜间隔）/（坡莫合金源极层），我们的实验表明如何不可重定向的自旋-轨道扭矩所产生的坡莫合金源极层（自旋-轨道扭矩的组成部分，不改变坡莫合金磁化旋转时）可以使用自旋扭矩铁磁共振（ST-FMR）与线形分析测量。我们发现，动态自旋泵的磁性层之间施加的扭矩的磁性层大或大于自旋轨道扭矩，因此，如果动态自旋泵被忽略的结果将是一个大的高估的自旋轨道扭矩。然而，这两种效应可以通过执行作为频率的函数的ST-FMR来分离。我们测量了从坡莫合金通过8 nm Cu间隔物到Co的自旋电流的不可重定向的自旋扭矩比ε Py = 0.04±0.01，以及与先前通过常规铁磁共振测量一致的动态自旋泵浦的强度。
Using a multilayer structure containing (cobalt detector layer)/(copper spacer)/(Permalloy source layer), we show experimentally how the non-reorientable spin-orbit torque generated by the Permalloy source layer (the component of spin-orbit torque that does not change when the Permalloy magnetization is rotated) can be measured using spin-torque ferromagnetic resonance (ST-FMR) with lineshape analysis. We find that dynamic spin pumping between the magnetic layers exerts torques on the magnetic layers as large or larger than the spin-orbit torques, so that if dynamic spin pumping is neglected the result would be a large overestimate of the spin-orbit torque. Nevertheless, the two effects can be separated by performing ST-FMR as a function of frequency. We measure a non-reorientable spin torque ratio ξPy = 0.04±0.01 for spin current flow from Permalloy through an 8 nm Cu spacer to the Co, and a strength of dynamic spin pumping that is consistent with previous measurements by conventional ferromagnetic resonance.