论文标题
在吉赫兹磁场下缺陷工程的Skyrmion的超快棘轮动力学
Ultrafast ratchet dynamics of skyrmion by defect engineering under gigahertz magnetic fields
论文作者
论文摘要
由微波磁场驱动的磁性空中运动的新型棘轮运动，其运动方向和速度可按场参数调谐，为驱动电导率较差的材料中的磁性天空提供了有希望的途径。但是，作为一种间接运动，与电流驱动的直接运动相比，Skyrmion棘轮运动速度通常很低。对于实际应用，询问是否存在实现磁性天空的超快棘轮运动的机制，以及如何将这种新型运动集成到赛道型天际设备中。在这项工作中，我们探讨了缺陷和边缘对GHz时随时间变化的磁场下磁空的棘轮运动的影响。我们证明，与散装区域相比，Skyrmion的棘轮运动不仅沿缺陷轨道或边缘进行引导，而且还具有显着的加速（超过十倍）。 Skyrmion棘轮运动速度沿着直轨/边缘/边缘达到100 m/s，沿着〜50吨的圆形边缘沿圆形边缘达到10^9 rad/s，与电流驱动的直接运动相当。此外，沿缺陷轨迹/边缘的Skyrmion棘轮运动可以通过场和缺陷参数来分别控制。基于时间平均的Skyrmion的硫素方程的分析验证了这种加速效应是由于垂直于Skyrmion运动的时间平均驱动力增加了，当它接近缺陷轨道或边缘时，类似于以由CORRINTS驱动的直接运动发现的缺陷轨迹或边缘。
The novel ratchet motion of magnetic skyrmions driven by microwave magnetic fields, with the motion direction and speed tunable by field parameters, provides a promising route to drive magnetic skyrmions in materials with poor conductivity. However, as an indirect motion, skyrmion ratchet motion speed is generally low in comparison with the direct motions driven by current. Toward practical applications, it is important to ask if there are mechanisms to realize ultrafast ratchet motion of magnetic skyrmions and how such novel motion can be integrated into racetrack-type skyrmion devices. In this work, we explore the effects of defects and edges on the ratchet motion of magnetic skyrmions under time-varying magnetic fields in GHz. We demonstrate that the ratchet motion of skyrmion is not only guided along the defect tracks or edges, but also with a remarkable speed-up (with a factor over ten) compared with that in the bulk region. The skyrmion ratchet motion speed reaches 100 m/s along a straight defect track/edge and 10^9 rad/s along a circular edge under a field of ~50 mT, comparable to those direct motions driven by currents. Moreover, the skyrmion ratchet motion along the defect track/edge can be facilely controlled by the field and defect parameters. Analysis based on time-averaged Thiele equation of skyrmion verifies that such a speed-up effect is due to the increased time-averaged driving force perpendicular to the skyrmion motion when it approaches the defect track or edge, analogous to that discovered in direct motions driven by currents.
