AI 中文总结
该研究在理论上禁戒自诱导自旋轨道转矩的对称无重金属MgO/NiFe/MgO三层膜中，观测到此类转矩，确定其源于1.8 nm的底部磁性死层，通过理论计算与实验吻合，证实NiFe本征自旋霍尔电导率足够，将死层用作功能组件，建立全铁磁体SOT路径。
AI 中文摘要
传统上，铁磁体中的自旋轨道转矩（SOTs）需要重金属层或工程化结构不对称性来打破反演对称性。在这项工作中，我们在名义上对称、无重金属的MgO/NiFe/MgO三层膜（一种理论上禁止此类转矩的结构）中观测到了强的自生成SOTs。结合谐波霍尔测量、SQUID磁强计和X射线光电子能谱，我们确定了对称性破缺的起源：底部界面处存在1.8 nm的磁性死层。关键的是，我们的数据与Kim和Lee提出的漂移扩散理论定量吻合，理论提取的死层厚度为1.2 nm，与结构表征结果一致。此外，密度泛函计算证实NiFe具有足够的本征自旋霍尔电导率，以支持观测到的自旋电流。这些结果将寄生死层重新定义为一种功能型自旋电子学组件，为标准磁性异质结构中的SOTs建立了一种通用的全铁磁体路径。
英文摘要
Conventionally, spin-orbit torques (SOTs) in ferromagnets require heavy-metal layers or engineered structural asymmetry to break inversion symmetry. In this work, we report the observation of robust, self-generated SOTs in a nominally symmetric, heavy-metal-free MgO/NiFe/MgO trilayer - a geometry where such torques are theoretically forbidden. By combining harmonic Hall measurements with SQUID magnetometry and X-ray photoelectron spectroscopy, we identify the symmetry-breaking origin: a 1.8 nm magnetic dead layer at the bottom interface. Crucially, we demonstrate a quantitative agreement between our data and the drift-diffusion theory predicted by Kim and Lee, yielding a theoretically extracted dead-layer thickness (1.2 nm) which matches structural characterization. Furthermore, density-functional calculations confirm that NiFe possesses sufficient intrinsic spin Hall conductivity to support the observed spin currents. These results reframe the parasitic dead layer as a functional spintronic component, establishing a universal, all-ferromagnetic route to SOTs in standard magnetic heterostructures.
