Magnetic Skyrmion Generation by Reflective Spin Wave Focusing

Abstract

We propose a method to generate magnetic skyrmions by focusing spin waves totally reflected by a curved film edge. The edge contour is derived to be parabolic and frequency-independent based on the identical magnonic path length principle. We performed micromagnetic simulations to verify our theoretical design. Under proper conditions, the reflected spin waves first converge at the focal point with the enhanced intensity leading to the emergence of magnetic droplets, which are then converted to magnetic skyrmion accompanied by a change in the topological charge. We numerically obtain the phase diagram of skyrmion generation with respect to the amplitude and frequency of the driving field. Our finding would be helpful for the design of spintronic devices combining the advantage of skyrmionics and magnonics.

Topological states and quantum effects in magnonics

“…), 可以求得自旋波焦点的 位置坐标: (identical MPL principle), 可以反推出完美透镜 的界面形状 [37] . 假设一自旋波束水平入射至界面, 在界面另一侧聚焦于一点, 如图8(a)所示, 则等磁 的微磁模拟结果; (d)焦点坐标随自旋波频率的变化 [128] coordinates as a function of the spin-wave frequency [128] .…”

“…最近研究表明DMI可以打破两种极化自旋波 模式的简并 [60,61] , 为实现磁子SG效应提供了可能. (c) the process of the skyrmion generated by the spin-wave focusing [37] .…”

“…最近研究还发现非共线 的拓扑磁结构可以诱导和增强磁子之间的非线性 耦合, 实现对束缚态自旋波的非局域探测和新奇磁 子非线性效应的探索 [31−36] . 反过来, 自旋波也可以 用来产生、驱动和翻转拓扑磁结构, 如利用自旋波 聚焦产生斯格明子 [37,38] , 利用磁子的自旋转移力矩 来驱动磁畴壁的运动和翻转磁矩方向 [39−41] , 利用 磁子的轨道转移力矩来驱动斯格明子的运动 [42] , 利用角向自旋波和径向自旋波来翻转磁涡旋和斯 格明子的极性等 [43−45] . 目前, 基于拓扑磁结构的磁 子学 [9,46] 已成为该领域的研究热点.…”

Spin dynamics in patterned magnetic multilayers with perpendicular magnetic anisotropy

“…Despite substantial success in terms of skyrmion nucleation using a number of di erent approaches, as mentioned above, the use of the SWs and spin dynamics for skyrmion formation has not been widely explored [219][220][221]. However, such an e ect can be very interesting in magnonics.…”

“…However, such an e ect can be very interesting in magnonics. Recently, Yao et al [221] showed the method of generating magnetic skyrmions in the e ective Co layer with DMI and PMA by focusing SWs totally re ected by a curved lm edge. This study numerically demonstrated that the accumulation of SW energy in the focal spot can be su cient to form or destroy a skyrmion.…”