Spin-orbit torque generated by spin-orbit precession effect in Py/Pt/Co tri-layer structure
Spin-orbit torque generated by spin-orbit precession effect in Py/Pt/Co tri-layer structure
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DOI：
10.1063/5.0002326
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发表时间：
2020-04-01
期刊：
影响因子：
6.1
通讯作者：
Chiba, D.
中科院分区：
文献类型：
--
作者：
Hibino, Y.;Hasegawa, K.;Chiba, D.
在本报告中，研究了坡莫合金 (Py)/Pt/Co 三层系统中电流引起的自旋轨道扭矩 (SOT)。除了 Pt 层中自旋霍尔效应产生的常规 SOT 之外，我们还观察到作用于面内磁化 Py 层的非常规 SOT 的明显存在，其中 SOT 的极性与垂直磁化 Co 的磁化强度相反。从其对称性和实验验证，我们得出结论，这种非常规 SOT，特别是类阻尼扭矩项，源于 Pt/Co 处自旋轨道进动效应产生的附加自旋电流。界面。此外，我们发现该 SOT 的极性很大程度上取决于铁磁材料/非磁性金属 (NM) 的界面结构，这可以通过选择 NM 材料来控制。界面结构依赖性显示出与先前报道的自旋轨道进动效应的第一原理计算结果一致的结果。我们的研究结果不仅拓宽了电流感应 SOT 的起源，而且为高效 SOT 器件的设计铺平了道路。
In this report, current-induced spin-orbit torques (SOTs) in a permalloy (Py)/Pt/Co tri-layer system are investigated. In addition to the conventional SOTs generated from the spin Hall effect in the Pt layer, we observed a distinct existence of unconventional SOT acting on the in-plane magnetized Py layer in which the polarity of SOT reverses with the magnetization of perpendicularly magnetized Co. From its symmetry and experimental verifications, we conclude that this unconventional SOT, especially the damping-like torque term, originates from the additional spin current generated by the spin-orbit precession effect at the Pt/Co interface. Moreover, we reveal that the polarity of this SOT strongly depends on the interface structure of the ferromagnetic material/non-magnetic metal (NM), which can be controlled by the choice of NM material. The interface structure dependence shows a consistent result with first principle calculations of the spin-orbit precession effect that were previously reported. Our findings not only broaden the origin of the current-induced SOT but also pave the way for the design of high-efficient SOT-based devices.