Spintronics has been extensively explored over the past decades, focusing primarily on the spin characteristic of the electron, while the orbital feature of the electron has been conventionally assumed to be quenched by the crystal field effect. Recently, studies have unveiled a fascinating discovery that orbital current, originating from orbital effects, can be generated in materials with weak spin‐orbit coupling by applying electric fields, enabling the manipulation of the ferromagnetic magnetization and induction of terahertz emission. This review highlights recent achievements in orbital effects, materials, and devices, beginning by discussing the mechanisms underlying orbital effects, e.g. the orbital Hall effect, orbital Rashba‐Edelstein effect, inverse orbital Hall effect, and inverse orbital Rashba‐Edelstein effect. Subsequently, a wide range of materials exhibiting orbital effects are classified and the orbital sources in them are identified. Furthermore, the review introduces the orbital torque devices and the orbital terahertz emitters, summarizing the in‐depth mechanisms of the orbital torque, orbital torque efficiency, and orbital diffusion length across various material structures. Additionally, the review presents strategies for enhancing orbital torque efficiency and driving magnetization switching. These efforts aim to explore the potential applications for orbitronic memory devices, computing components, and terahertz emitters.

中文翻译：

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轨道机械：机构、材料和设备


在过去的几十年里，自旋电子学得到了广泛的探索，主要集中在电子的自旋特性上，而电子的轨道特征通常被认为被晶场效应淬灭。最近，研究揭示了一个有趣的发现，即通过施加电场，可以在自旋-轨道耦合较弱的材料中产生源自轨道效应的轨道电流，从而能够操纵铁磁化和太赫兹发射的感应。本文重点介绍了轨道效应、材料和器件方面的最新成就，首先讨论了轨道效应的潜在机制，例如轨道霍尔效应、轨道 Rashba-Edelstein 效应、逆轨道霍尔效应和逆轨道 Rashba-Edelstein 效应。随后，对表现出轨道效应的各种材料进行分类，并确定其中的轨道源。此外，综述介绍了轨道扭矩器件和轨道太赫兹发射器，总结了各种材料结构的轨道扭矩、轨道扭矩效率和轨道扩散长度的深入机制。此外，该综述还提出了提高轨道扭矩效率和驱动磁化开关的策略。这些工作旨在探索轨道存储设备、计算组件和太赫兹发射器的潜在应用。