Lee Dong-Kyu, Lee Kyung-Jin
Department of Materials Science and Engineering, Korea University, Seoul, 02841, Korea.
KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, 02841, Korea.
Sci Rep. 2020 Feb 4;10(1):1772. doi: 10.1038/s41598-020-58669-1.
In ferromagnetic trilayers, a spin-orbit-induced spin current can have a spin polarization of which direction is deviated from that for the spin Hall effect. Recently, magnetization switching in ferromagnetic trilayers has been proposed and confirmed by the experiments. In this work, we theoretically and numerically investigate the switching current required for perpendicular magnetization switching in ferromagnetic trilayers. We confirm that the tilted spin polarization enables field-free deterministic switching at a lower current than conventional spin-orbit torque or spin-transfer torque switching, offering a possibility for high-density and low-power spin-orbit torque devices. Moreover, we provide analytical expressions of the switching current for an arbitrary spin polarization direction, which will be useful to design spin-orbit torque devices and to interpret spin-orbit torque switching experiments.
在铁磁三层膜中，自旋轨道诱导的自旋电流可以具有自旋极化，其方向与自旋霍尔效应的方向不同。最近，铁磁三层膜中的磁化翻转已被提出并通过实验得到证实。在这项工作中，我们从理论和数值上研究了铁磁三层膜中垂直磁化翻转所需的翻转电流。我们证实，倾斜的自旋极化能够在比传统自旋轨道扭矩或自旋转移扭矩翻转更低的电流下实现无场确定性翻转，这为高密度和低功耗自旋轨道扭矩器件提供了可能性。此外，我们给出了任意自旋极化方向下翻转电流的解析表达式，这将有助于设计自旋轨道扭矩器件并解释自旋轨道扭矩翻转实验。
