论文标题
Terahertz自旋动力学由光旋转轨道扭矩驱动
Terahertz spin dynamics driven by an optical spin-orbit torque
论文作者
论文摘要
旋转扭矩是自旋装置中自旋操作的核心。在这里，我们研究了光学自旋轨道扭矩的存在，这是一种相对论的自旋扭矩，源自旋转的施加场与自旋的自旋轨道耦合。我们比较非层次的Zeeman扭矩与相对论的光学自旋轨道扭矩对通过圆形极化激光脉冲激发的铁磁系统的相对论光学旋转扭矩。后一个扭矩取决于光和尺度的螺旋，同时与频率成反比。我们的结果表明，光旋转轨道扭矩可以在旋转上提供扭矩，该扭矩与Zeeman扭矩相等。此外，温度依赖性计算表明，光旋转轨道扭矩的影响随温度的升高而降低。但是，这种效果在铁磁系统中也不会消失，即使是高于其居里温度的。
Spin torques are at the heart of spin manipulations in spintronic devices. Here, we examine the existence of an optical spin-orbit torque, a relativistic spin torque originating from the spin-orbit coupling of an oscillating applied field with the spins. We compare the effect of the nonrelativistic Zeeman torque with the relativistic optical spin-orbit torque for ferromagnetic systems excited by a circularly polarised laser pulse. The latter torque depends on the helicity of the light and scales with the intensity, while being inversely proportional to the frequency. Our results show that the optical spin-orbit torque can provide a torque on the spins, which is quantitatively equivalent to the Zeeman torque. Moreover, temperature dependent calculations show that the effect of optical spin-orbit torque decreases with increasing temperature. However, the effect does not vanish in a ferromagnetic system, even above its Curie temperature.
