基于Sagnac磁光技术和谐波霍尔测量的稀土合成亚铁磁体中界面调控的自旋轨道转矩
Interface-Controlled Spin-Orbit Torques in Rare-Earth Synthetic Ferrimagnets Probed by Sagnac Magneto-Optics and Harmonic Hall Measurements
浏览论文内容
中文总结 AI 辅助
本研究利用Sagnac磁光技术和谐波霍尔测量探究Co/Gd基合成亚铁磁体，明确界面对自旋轨道转矩的调控作用，证实Gd层在转矩产生中的功能，实现低电流密度下的SOT开关，为优化低功耗自旋电子器件提供新平台。
中文摘要 AI 辅助
自旋轨道转矩（SOT）为自旋电子器件中的磁化操控提供了高效途径，其准确定量至关重要。本研究采用互补的磁输运与磁光技术对钴/钆（Co/Gd）基合成亚铁磁体展开研究，运用Sagnac磁光干涉法直接定量电流诱导的磁化倾斜，并提取类阻尼SOT有效场。Sagnac测量在不同Co/Gd及Gd/Pt/Co异质结构上与谐波霍尔分析结果吻合良好，提供了不依赖电输运信号的类阻尼SOT有效场定量测定方法。通过改变Gd厚度与多层堆叠顺序，研究表明类阻尼转矩受稀土与重金属界面处的自旋输运及角动量转换强烈影响；在预期常规Pt自旋霍尔贡献会发生补偿的Gd/Pt/Co/Pt结构中观测到有限转矩，凸显了Gd层在SOT产生中的主动作用。此外，界面工程可在含2纳米厚Co层的Gd/Pt/Co/Al异质结构中实现垂直磁各向异性，使电流诱导SOT开关的电流密度达8-10 MA/cm²。这些结果确立了稀土基合成亚铁磁体为工程化自旋轨道现象及优化低功耗自旋电子器件的通用平台。
英文摘要
Spin-orbit torque (SOT) provides an efficient route for manipulating magnetization in spintronic devices, and its accurate quantification is essential. Here, we investigate Co/Gd-based synthetic ferrimagnets using complementary magnetotransport and magneto-optical techniques. We use a Sagnac magneto-optical interferometry method to directly quantify current-induced magnetization tilting and extract the damping-like SOT effective field. The Sagnac measurements show good agreement with harmonic Hall analysis across different Co/Gd and Gd/Pt/Co heterostructures, providing a quantitative determination of the damping-like SOT effective field that does not rely on electrical transport signatures. By varying the Gd thickness and multilayer stacking order, we demonstrate that the damping-like torque is strongly influenced by spin transport and angular momentum conversion at rare-earth and heavy-metal interfaces. The observation of a finite torque in Gd/Pt/Co/Pt structures, where conventional Pt spin Hall contributions are expected to compensate, highlights the active role of the Gd layer in SOT generation. Furthermore, interface engineering enables perpendicular magnetic anisotropy in Gd/Pt/Co/Al heterostructures with a 2-nm-thick Co layer, allowing current-induced SOT switching at current densities of 8-10 MA/cm$^2$. These results establish rare-earth-based synthetic ferrimagnets as a versatile platform for engineering spin-orbit phenomena and optimizing low-power spintronic devices.
