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具有强自旋轨道耦合（SOC）效应的稀土金属因其可以产生自旋霍尔矩有望在低功耗磁信息存储、逻辑运算和神经元模拟器件中发挥潜在作用。本文选用重稀土金属镝（Dy）作为自旋源层，[Co/Pt]3作为磁性层构建Dy/Pt/[Co/Pt]3垂直磁化多层膜，探究了不同Dy层厚度对体系自旋轨道矩（SOT）效率以及SOT驱动磁矩翻转的影响规律。利用谐波锁相技术分析得到稀土金属Dy的内禀自旋霍尔角为0.260±0.039，自旋扩散长度为2.234±0.383 nm，表明Dy可以作为理想的自旋源材料。此外，基于体系类阻尼SOT效率的有效提升，临界翻转电流密度随Dy层厚度增加而逐渐降低，最低约为5.3×106 A/cm2。以上研究结果证实稀土金属Dy存在强的自旋霍尔效应，为设计低功耗SOT基自旋电子器件提供了有效路径。Spin-orbit torque (SOT) based on the spin-orbit coupling (SOC) effect has gained increasing attention in magnetic information storage, logical operation and neuron simulation devices because it can effectively manipulate magnetization switching, chiral magnetic domain wall, and magnetic skyrmion motions. Further improvement of the SOT efficiency and reduction of the driving current density are crucial scientific problems to be solved for high-density and low-power applications of SOT-based spintronic devices. The heavy rare-earth metal dysprosium (Dy) possesses a relatively strong SOC due to the partially filled f orbital electrons (4f10), which is expected to generate spin Hall torques. In this paper, the impact of Dy thicknesses on the SOT efficiency and SOT-driven magnetic reversal was explored in the Dy/Pt/[Co/Pt]3 magnetic multilayers, where the rare-earth Dy and [Co/Pt]3 were used as the spin-source layer and the perpendicularly magnetized ferromagnetic layer, respectively. A series of Dy/Pt/[Co/Pt]3 heterostructures with various Dy layer thicknesses (tDy) of 1, 3, 5 and 7 nm were fabricated by ultrahigh-vacuum magnetron sputtering. The perpendicular magnetic anisotropy, SOT efficiency, spin Hall angle and current-induced magnetization switching were characterized using the magnetic property and electrical transport measurements. The results showed that the switching field and magnetic anisotropic field decreased with an increase in tDy, revealing that the magnetic parameters can be regulated by the bottom Dy layer due to their structural sensitivity. However, both damping-like SOT efficiency and effective spin Hall angle (θSHeff) gradually increased with increasing tDy, indicating that the rare-earth Dy can provide additional spin current to enhance the SOT efficiency apart from the contribution of Pt/[Co/Pt]3. Particularly, the maximum θSHeff of 0.379±0.008 was achieved when tDy was 7 nm. According to the fitting analysis of the drift-diffusion model, the intrinsic spin Hall angle and spin diffusion length of the rare-earth Dy were extracted to be 0.260±0.039 and 2.234±0.383 nm, respectively, suggesting that Dy can be used as an ideal spin-source material. In addition, the critical switching current density (Jc) gradually decreased with the increase in tDy, and Jc reached a minimum value of approximately 5.3×106 A/cm2 at tDy=7 nm, which is primarily attributed to the increase of the damping-like SOT and slight decrease of the switching field. These results experimentally demonstrate a strong spin Hall effect of the rare-earth Dy, and provide a feasible route for designing SOT-based spintronic devices with low-power dissipation.
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