MIIT Key Laboratory of Advanced Display Materials and Devices, Institute of Optoelectronics & Nanomaterials, College of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China.
Nanoscale Physics & Devices Laboratory, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
Nat Commun. 2018 Jul 2;9(1):2569. doi: 10.1038/s41467-018-05057-z.
Enhancing the in-plane current-induced torque efficiency in inversion-symmetry-breaking ferromagnetic heterostructures is of both fundamental and practical interests for emerging magnetic memory device applications. Here, we present an interface-originated magnetoelectric effect, the orbital Rashba-Edelstein effect, for realizing large torque efficiency in Pt/Co/SiO/Pt films with strong perpendicular magnetic anisotropy (PMA). The key element is a pronounced Co 3d orbital splitting due to asymmetric orbital hybridization at the Pt/Co and Co/SiO interfaces, which not only stabilizes the PMA but also produces a large orbital torque upon the Co magnetization with current injection. The torque efficiency is found to be strongly magnetization direction- and temperature-dependent, and can reach up to 2.83 at room temperature, which is several times to one order of magnitude larger than those previously reported. This work highlights the active role of the orbital anisotropy for efficient torque generation and indicates a route for torque efficiency optimization through orbital engineering.
增强反演对称破缺铁磁异质结构中的面内电流感应扭矩效率，对于新兴的磁存储器件应用具有基础和实际的意义。在这里，我们提出了一种源于界面的磁电效应，轨道 Rashba-Edelstein 效应，用于在具有强垂直各向异性（PMA）的 Pt/Co/SiO/Pt 薄膜中实现大的扭矩效率。关键因素是由于 Pt/Co 和 Co/SiO 界面处的不对称轨道杂化导致的显著 Co 3d 轨道劈裂，这不仅稳定了 PMA，而且在 Co 磁化时通过电流注入产生大的轨道扭矩。发现扭矩效率强烈依赖于磁化方向和温度，可以在室温下达到 2.83，比以前报道的大几个数量级到一个数量级。这项工作强调了轨道各向异性在高效扭矩产生中的积极作用，并指出了通过轨道工程优化扭矩效率的途径。
