消磁场对纳米铁磁线磁畴壁动力学行为的影响

为了实现基于磁畴壁运动的自旋电子学装置, 掌握磁畴壁动力学行为是重要争论之一.研究了在外磁场驱动下L-型纳米铁磁线磁畴壁的动力学行为. 通过微磁学模拟,在各种外磁场的驱动下考察了纳米铁磁线磁畴壁的动力学特性; 在较强外磁场的驱动下, 在不同厚度纳米线上考察了纳米线表面消磁场对磁畴壁动力学行为的影响. 为了进一步证实消磁场对磁畴壁动力学的影响, 在垂直于纳米线表面的外磁场辅助下分析了磁畴壁的动力学行为变化. 结果表明, 随着纳米线厚度和外驱动磁场强度的增加, 增强了纳米线表面的消磁场的形成, 使得磁畴壁内部自旋结构发生周期性变化, 导致磁畴壁在纳米线上传播时出现Walker崩溃现象. 在垂直于纳米线表面的外磁场辅助下, 发现辅助磁场可以调节消磁场的强度和方向. 这意味着利用辅助磁场可以有效地控制纳米铁磁线磁畴壁的动力学行为.

Influences of the demagnetizing field on dynamic behaviors of the magnetic domain wall in ferromagnetic nanowires

Understanding of magnetic domain wall dynamic behavior is one of the important issues in the realization of spintronic device based on domain wall motion. We investigate the dynamic behaviors of the magnetic domain wall propagation in L-shaped ferromagnetic nanowires under external magnetic driving fields. By micromagnetic simulation, we observe a dynamic characteristic of the magnetic domain wall in a ferromagnetic nanowire with varying the external field. By changing the nanowire thickness, we examine the influence of the demagnetizing field from the nanowire surface on the domain wall dynamics under a magnetic driving field after Walker breakdown field. Using an auxilliary magnetic field perpendicular to the nanowires, we analyze the effect of the demagnetizing field on the domain wall dynamic behaviors. The results show that the stronger external field or the thicker nanowire can enhance the generation of the demagnetizing field on the nanowire surface, leading to the occurrence of the Walker breakdown phenomenon with the periodic change of the inner spin structure of the domain wall during the domain wall propagation in the nanowires. By using an auxilliary magnetic field perpendicular to the nanowires, we find that the strength and the direction of the demagnetizing field can be modulated. It implies that the dynamic behavior of domain wall propagation in the nanowire is controllable.