Kim Tae-Hoon, Zhao Haijun, Ong Phuong-Vu, Jensen Brandt A, Cui Baozhi, King Alexander H, Ke Liqin, Zhou Lin
Ames Laboratory, U.S. Department of Energy, Ames, Iowa 50011, United States.
Department of Materials Science and Engineering, Chonnam National University, Gwangju 61186, Republic of Korea.
Nano Lett. 2021 Jul 14;21(13):5547-5554. doi: 10.1021/acs.nanolett.1c00923. Epub 2021 Jun 29.
The particle-like magnetic skyrmion or skyrmion lattice (SkX) formation has promoted strong application and fundamental science interests. Despite extensive research, the kinetic of the SkX development is much less understood because of the ultrafast spin rotation and high sensitivity to external perturbations. Here, using Lorentz transmission electron microscopy, we successfully measured the dynamics of SkX formation from the conical phase with precise control of both the temperature and the magnetic field. We discovered that the Avrami equation can accurately describe the transition process with an initial Avrami constant around 1, suggesting that the rate-limiting step for the quasiparticle lattice formation is one-dimensional heterogeneous nucleation of individual skyrmions. A modified Arrhenius rate law is established, with an energy barrier that has a square-root dependence on temperature and a quadratic dependence on the magnetic field. This study paves the way toward precise and predictable manipulation of topological spin structures.
粒子状磁斯格明子或斯格明子晶格（SkX）的形成引发了强烈的应用和基础科学兴趣。尽管进行了广泛研究，但由于超快的自旋旋转和对外部扰动的高敏感性，SkX发展的动力学仍鲜为人知。在此，我们使用洛伦兹透射电子显微镜，在精确控制温度和磁场的情况下，成功测量了从锥形相形成SkX的动力学过程。我们发现，阿弗拉米方程可以准确描述转变过程，初始阿弗拉米常数约为1，这表明准粒子晶格形成的速率限制步骤是单个斯格明子的一维非均相成核。我们建立了一个修正的阿伦尼乌斯速率定律，其能量势垒对温度呈平方根依赖关系，对磁场呈二次方依赖关系。这项研究为精确且可预测地操控拓扑自旋结构铺平了道路。
