Anomalous sign inversion of spin-orbit torque in ferromagnetic/nonmagnetic bilayer systems due to self-induced spin-orbit torque
Anomalous sign inversion of spin-orbit torque in ferromagnetic/nonmagnetic bilayer systems due to self-induced spin-orbit torque
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DOI：
10.1103/physrevb.106.174418
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发表时间：
2022-11-17
影响因子：
3.7
通讯作者：
Ando, Yuichiro
中科院分区：
文献类型：
--
作者：
Aoki, Motomi;Shigematsu, Ei;Ando, Yuichiro
铁磁层中的自感自旋轨道矩（SI-SOT）在计算相邻铁磁层的自旋霍尔角（SHA）时被忽略了。在这项工作中，我们观察到的自旋扭矩铁磁共振由于增强SI-SOT的总SOT的异常符号反转，并成功地合理化的符号反转通过理论计算，考虑在NM和FM层的SHE。研究结果表明，使用FM层的SHA符号是相同的NM实现有效的SOT磁化开关的协助下的SI-SOT。对于弱导电NM层，SI-SOT的贡献变得突出，并且不考虑SI-SOT的常规分析可能高估NM层的SHA超过150倍。
Self-induced spin-orbit torques (SI-SOTs) in ferromagnetic (FM) layers have been overlooked when estimating the spin Hall angle (SHA) of adjacent nonmagnetic (NM) layers. In this work, we observe anomalous sign inversion of the total SOT in the spin-torque ferromagnetic resonance due to the enhanced SI-SOT, and successfully rationalize the sign inversion through a theoretical calculation considering the SHE in both the NM and FM layers. The findings show that using an FM layer whose SHA sign is the same as that of the NM achieves efficient SOT-magnetization switching with the assistance of the SI-SOT. The contribution of the SI-SOT becomes salient for a weakly conductive NM layer, and conventional analyses that do not consider the SI-SOT can overestimate the SHA of the NM layer by a factor of more than 150.