Observation of long-range orbital transport and giant orbital torque
Observation of long-range orbital transport and giant orbital torque
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DOI：
10.1038/s42005-023-01139-7
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发表时间：
2023-02-06
影响因子：
5.5
通讯作者：
Ando, Kazuya
中科院分区：
文献类型：
--
作者：
Hayashi, Hiroki;Jo, Daegeun;Ando, Kazuya
现代自旋电子学依赖于通过自旋轨道耦合产生自旋电流。自旋电流的产生被认为是由电流诱导的轨道动力学触发的，该动力学控制着从晶格到固体中电子的角动量转移。轨道响应在角动量动力学中的基本作用表明了自旋流的轨道对应物：轨道流的重要性。然而，其存在的证据一直难以捉摸。在这里，我们展示了巨大的轨道电流的产生，并揭示了轨道响应的基本特征。我们的实验和理论表明，轨道电流传播的距离比自旋电流超过一个数量级的铁磁体和非磁体。此外，我们发现，轨道电流使电操纵的磁化效率显着高于自旋对应。这些发现为利用固态器件中的轨道输运和自旋轨道耦合动力学的轨道电子学打开了大门。自旋电流的产生对于自旋电子器件的成功开发是不可或缺的，然而轨道对应物也被期望是潜在的有利因素。在这里，使用Ni/Ti双层，结合紧密结合计算，作者研究了由于轨道霍尔效应而发生的自旋扭矩效率，观察到轨道电流可以传播比自旋电流更长的距离。
Modern spintronics relies on the generation of spin currents through spin-orbit coupling. The spin-current generation has been believed to be triggered by current-induced orbital dynamics, which governs the angular momentum transfer from the lattice to the electrons in solids. The fundamental role of the orbital response in the angular momentum dynamics suggests the importance of the orbital counterpart of spin currents: orbital currents. However, evidence for its existence has been elusive. Here, we demonstrate the generation of giant orbital currents and uncover fundamental features of the orbital response. We experimentally and theoretically show that orbital currents propagate over longer distances than spin currents by more than an order of magnitude in a ferromagnet and nonmagnets. Furthermore, we find that the orbital current enables electric manipulation of magnetization with efficiencies significantly higher than the spin counterpart. These findings open the door to orbitronics that exploits orbital transport and spin-orbital coupled dynamics in solid-state devices.The generation of spin-current is integral for the successful development of spintronic devices however the orbital counterpart is also expected to be potentially advantageous. Here, using Ni/Ti bilayers, in combination with tight binding calculations, the authors investigate the spin torque efficiency that occurs as a result of the orbital Hall effect, observing that orbital currents can propagate over longer distances than the spin currents.