AI 中文总结
研究利用轨道霍尔效应在Mo/CoGd双层中实现无外加转换层的无场磁化反转，通过Mo提供电流，CoGd层实现转换与开关介质功能，增加Mo厚度可提高扭矩效率，为低功耗轨道电子存储设备提供了紧凑平台。
AI 中文摘要
自旋霍尔效应为电控制磁化提供了既定途径，而轨道霍尔效应是强大但探索较少的角动量源。在直接的轨道扭矩架构中实现无场确定性开关仍具有挑战性。本文展示了在Mo/CoGd双层中，无需单独的轨道-自旋转换层，在宽温度范围内由轨道霍尔电流驱动的开关。Mo作为轨道和自旋电流源，因自旋轨道耦合弱，自旋贡献不足。相邻亚铁磁CoGd层提供轨道-自旋转换和垂直开关介质。平面霍尔和电流诱导环移测量揭示了源于界面对称性破缺的大量非常规z极化类阻尼扭矩。增加Mo厚度可提高扭矩效率，实现低至2.51 x 10^6 A cm^-2临界电流密度的无场确定性开关。结果表明Mo/CoGd双层是轨道电流开关的紧凑平台，指向低功耗轨道电子存储设备。
英文摘要
The spin Hall effect provides a well-established route for electrical magnetization control, while the orbital Hall effect offers a powerful yet less explored source of angular momentum. Achieving field-free deterministic switching in straightforward orbital-torque architectures remains challenging. Here, we demonstrate orbital-Hall-current-driven switching in a Mo/CoGd bilayer without the need for a separate orbital-to-spin conversion layer across a wide temperature range. In this simplified geometry, Mo serves as both an orbital and spin current source. However, the spin contribution is insufficient due to weak spin-orbit coupling, which is consistent with first-principles calculations predicting a large orbital Hall conductivity. The adjacent ferrimagnetic CoGd layer provides both orbital-to-spin conversion and the perpendicular switching medium. Planar Hall and current-induced loop-shift measurements reveal a substantial unconventional z-polarized damping-like torque originating from interfacial symmetry breaking. Increasing the Mo thickness from 0.2 to 2 nm increases torque efficiency by approximately 31% (y-polarized) and 71% (z-polarized) components. This enhancement enables field-free deterministic switching with a critical current density down to 2.51 x 10^6 A cm^-2. Our results establish Mo/CoGd bilayers as a compact platform for orbital-current switching and point toward low-power orbitronic memory devices.
Comments19 pages, 4 figures
