Dong Li

Orbital current in light metals has attracted considerable attention as an alternative tool to switch the magnetization of ferromagnets. However, the manipulation of orbital torque efficiency, which is a key aspect of novel spin-orbitronic devices, remains a challenge. Here, the reversible modulation of orbital torque at room temperature is demonstrated in perpendicularly magnetized Ta/Pt/Co/Cu–CuOx/MoOx Hall bar devices. By applying a negative electric field, the orbital torque efficiency of a device with a Cu–CuOx thickness of 3 nm can be significantly enhanced by a factor of ∼4.64. This outstanding result is attributed to the applied electric fields driving the migration of oxygen ions, which controls the distance between the Cu/CuOx interface and the Co layer, as well as the formation or reduction of an antiferromagnetic CoOx layer at the Co surface. Consequently, the injection efficiency of the orbital current is controlled. In addition, the critical magnetization switching current density is reduced by ∼36% by applying an electric field. These findings provide a pathway for implementing electrically driven magnetization switching in potential applications while also opening new avenues for the development of spin-orbitronic devices.

轨道霍尔磁电阻效应是研究轨道流输运和轨道角动量-磁矩相互作用的有效手段，近年来引起研究者广泛关注.但轻金属/磁性材料异质结构中受限于轨道流-自旋流转换效率低，磁电阻数值普遍偏小.本文中，我们利用轻金属Cr的轨道霍尔效应提供轨道流，通过重金属Pt提升轨道流-自旋流转换效率，在垂直磁化Cr(t)/Co/Pt₃多层膜体系中获得室温下1.6×10^-3的轨道霍尔磁电阻，高出以前同类实验报道1个数量级.同时，利用Cr厚度与磁电阻变化关系拟合出Cr中轨道流扩散长度约为0.93 nm，远小于以前的实验报道.进一步，在Cr/Pt/Co/Pt多层膜中，利用重金属Pt插层提高轨道流-自旋流转换效率，通过轨道霍尔效应和自旋霍尔效应共同作用，有效提升体系磁电阻值达到4.5×10^-3.这些结果对理解轨道-磁序耦合机制以及发展低功耗自旋轨道电子器件提供重要实验依据.

Electric-field control of magnetization switching holds great promise for the development of spintronic devices due to its intrinsically low power consumption. Here, we demonstrate the efficient and reversible manipulation of field-free perpendicular magnetization switching through the electric-field driven migration of oxygen ions within the Pt/Co/CuOx/MoOx system. The antiferromagnetic CoO layer at the Co/CuOx interface modulated by the gate voltage provides an exchange bias field, enabling field-free current-driven magnetization switching. The field-free switching ratio can be effectively enhanced by applying a negative gate voltage, with the maximum value being 62.7%, which is five times larger than that in the initial state without applying gate voltage. The electric-field driven migration of oxygen ions, causing enhanced/reduced oxidation at the Co/CuOx interface, leads to the reversible tunability of the field-free perpendicular magnetization switching. These results offer an approach to effectively control perpendicular magnetization switching without the need for a magnetic field, holding significant implications for low-power spintronic applications.

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。

Current-induced spin–orbit torque (SOT) has attracted much attention due to its potential applications in energy-efficient logic, memory, and artificial neuron devices. In this work, we report an enhanced SOT efficiency in perpendicularly magnetized Pt/Sm/Co/Ta heterostructures by inserting a light rare-earth Sm layer with large spin–orbit coupling. A series of Ta/Pt/Sm/Co/Ta samples with the Sm layer thickness (tSm) of 0, 0.6, 1.2, and 1.6 nm were prepared using direct-current magnetron sputtering. Perpendicular magnetic anisotropy, SOT efficiency, and current-driven magnetization reversal were characterized using electrical transport methods based on the anomalous Hall effect. The experimental results indicated that the switching field and magnetic anisotropic field decreased monotonically with an increase in tSm, while the damping-like effective field and effective spin Hall angle (θSHeff) gradually increased. It demonstrates that interface modification with a Sm layer can improve the SOT efficiency and reduce the pinning potential barrier. Owing to the enhanced SOT and reduced pinning field, the critical switching current density (Jc) exhibits a steady decline when increasing tSm. In particular, the lowest Jc of approximately 7.83 × 106 A/cm2 was obtained when tSm was 1.6 nm. X-ray photoelectron spectroscopy revealed that electron transfer occurred between the Co, Pt, and Sm layers, which may be primarily responsible for the enhanced SOT by interface alloying to effectively strengthen the spin Hall effect of Sm and/or Pt. Our results provide a strategy for improving SOT efficiency and reducing Jc by interface alloying in SOT-based spintronic devices.

This study presents experimental evidence of the substantial modulation of ferromagnetism and spin–orbit torque (SOT) efficiency in a Ta/Pt/Co/Ta/In2Se3 heterostructure with perpendicular magnetic anisotropy through light irradiation. An increase in SOT efficiency of ∼20% and a reduction in critical switching current density of ∼52% were observed. The significant modulation primarily originates from the photostrictive effect of a van der Waals-layered ferroelectric In2Se3 layer, which is assisted by thermal effects under light irradiation. The present research provides a potential approach to modulating magnetism and SOT efficiency for energy-efficient spintronic devices.

Metal oxide electronic interactions in composite electrocatalysts have a considerable impact on their catalytic capability. In this study, we successfully synthesized an electrocatalytic material composed of MoO ₃ /C species‐supported Pd nanoparticles (Pd‐MoO ₃ /C) using a convenient hydrothermal method, which exhibited excellent catalytic activities for both ethanol oxidation and oxygen reduction in KOH media. The specific activity of Pd‐MoO ₃ /C toward ethanol oxidation with MoO ₃ loading (40 wt%) was ~ 2.6 times greater than that for the commercial Pd/C (10 wt%) with the same Pd content. In particular, the activity could effectively hold up to ~ 60% of its maximum activity after 500‐cycle tests, demonstrating improved cyclical stability. Notably, the fast electron transfer kinetics toward oxygen reduction for Pd‐MoO ₃ /C (40%) were also comparable to those of commercial Pt/C (20 wt%) catalysts. These superior electrochemical features are primarily derived from the stronger electronic coupling between Pd and MoO ₃ through charge transfer, which can supply more active centers and improve the anti‐poisoning ability. Meanwhile, the MoO ₃ species in the Pd‐MoO ₃ /C composite may provide additional benefits in terms of electrical conductivity and dispersion.