Terahertz spintronics offers the prospect of devices which are both faster and more energy-efficient. A promising route to achieve this goal is to exploit current-induced spin-orbit torques. However, the high-frequency properties of these quantities remain unexplored both experimentally and theoretically, within a realistic material-specific approach. Here we investigate the dynamical transverse components of the torques and uncover contributions longitudinal to the magnetic moment capable of changing its magnitude. We show that, while the torques can be drastically altered in the dynamical regime, the effective magnetic fields that accompany them present a frequency-independent behaviour, ranging from the static limit up to the terahertz domain — including the ferromagnetic resonance of the system. The outcomes of this work point to new ways to control magnetic units in next-generation spintronic devices.

太赫兹自旋电子学提供了更快，更节能的设备前景。实现该目标的一种有希望的途径是利用电流感应的自旋轨道扭矩。但是，在实际的特定于材料的方法中，无论是实验还是理论上，这些量的高频特性均未得到开发。在这里，我们研究了扭矩的动态横向分量，并揭示了能够改变其大小的磁矩的纵向贡献。我们表明，虽然扭矩可以在动态范围内急剧变化，但伴随它们的有效磁场却呈现出与频率无关的行为，其行为范围从静态极限到太赫兹域（包括系统的铁磁谐振）。