Takeuchi Yutaro, Yamane Yuta, Yoon Ju-Young, Itoh Ryuichi, Jinnai Butsurin, Kanai Shun, Ieda Jun'ichi, Fukami Shunsuke, Ohno Hideo
Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, Aoba-ku, Sendai, Japan.
WPI-Advanced Institute for Materials Research, Tohoku University, Sendai, Japan.
Nat Mater. 2021 Oct;20(10):1364-1370. doi: 10.1038/s41563-021-01005-3. Epub 2021 May 13.
Electrical manipulation of magnetic materials by current-induced spin torque constitutes the basis of spintronics. Here, we show an unconventional response to spin-orbit torque of a non-collinear antiferromagnet MnSn, which has attracted attention owing to its large anomalous Hall effect despite a vanishingly small net magnetization. In epitaxial heavy-metal/MnSn heterostructures, we observe a characteristic fluctuation of the Hall resistance under the application of electric current. This observation is explained by a rotation of the chiral-spin structure of MnSn driven by spin-orbit torque. We find that the variation of the magnitude of anomalous Hall effect fluctuation with sample size correlates with the number of magnetic domains in the MnSn layer. In addition, the dependence of the critical current on MnSn layer thickness reveals that spin-orbit torque generated by small current densities, below 20 MA cm, effectively acts on the chiral-spin structure even in MnSn layers that are thicker than 20 nm. The results provide additional pathways for electrical manipulation of magnetic materials.
通过电流感应自旋扭矩对磁性材料进行电操纵构成了自旋电子学的基础。在此，我们展示了非共线反铁磁体MnSn对自旋轨道扭矩的一种非常规响应，尽管其净磁化强度极小，但因其巨大的反常霍尔效应而备受关注。在外延重金属/MnSn异质结构中，我们观察到在施加电流时霍尔电阻的特征波动。这一观察结果可通过自旋轨道扭矩驱动的MnSn手性自旋结构的旋转来解释。我们发现反常霍尔效应波动幅度随样品尺寸的变化与MnSn层中的磁畴数量相关。此外，临界电流对MnSn层厚度的依赖性表明，即使在厚度超过20 nm的MnSn层中，低于20 MA/cm的小电流密度产生的自旋轨道扭矩也能有效地作用于手性自旋结构。这些结果为磁性材料的电操纵提供了额外的途径。
