RIKEN Center for Emergent Matter Science (CEMS) , Wako 351-0198, Japan.
Research and Development Group, Hitachi Ltd., Hatoyama 350-0395, Japan.
Nano Lett. 2018 Feb 14;18(2):929-933. doi: 10.1021/acs.nanolett.7b04312. Epub 2018 Jan 22.
To utilize magnetic skyrmions, nanoscale vortex-like magnetic structures, experimental elucidation of their dynamics against current application in various circumstances such as in confined structure and mixture of different magnetic phases is indispensable. Here, we investigate the current-induced dynamics of the coexistence state of magnetic skyrmions and helical magnetic structure in a thin plate of B20-type helimagnet FeGe in terms of in situ real-space observation using Lorentz transmission electron microscopy. Current pulses with various heights and widths were applied, and the change of the magnetic domain distribution was analyzed using a machine-learning technique. The observed average driving direction of the two-magnetic-state domain boundary is opposite to the applied electric current, indicating ferromagnetic s-d exchange coupling in the spin-transfer torque mechanism. The evaluated driving distance tends to increase with increasing the pulse duration time, current density (>1 × 10 A/m), and sample temperature, providing valuable information about hitherto unknown current-induced dynamics of the skyrmion-lattice ensemble.
为了利用磁斯格明子（一种纳米级旋涡状磁性结构），必须在各种情况下（如在受限结构中和不同磁相的混合物中）对其动力学进行实验阐明，以应用电流。在这里，我们使用洛伦兹透射电子显微镜进行原位实空间观察，研究了 B20 型手性磁铁 FeGe 薄片中磁斯格明子和螺旋磁结构共存状态的电流诱导动力学。施加了具有不同高度和宽度的电流脉冲，并使用机器学习技术分析了磁畴分布的变化。观察到的双磁态畴界的平均驱动方向与外加电流相反，表明在自旋转移扭矩机制中存在铁磁 s-d 交换耦合。评估的驱动距离似乎随脉冲持续时间、电流密度（>1×10 A/m）和样品温度的增加而增加，为迄今未知的斯格明子晶格整体的电流诱导动力学提供了有价值的信息。
