Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials Science and Engineering, Beihang University, Beijing, 100191, P. R. China.
School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, P. R. China.
Adv Sci (Weinh). 2023 Jan;10(3):e2205574. doi: 10.1002/advs.202205574. Epub 2022 Nov 20.
Nontrivial chiral spin textures with nanometric sizes and novel characteristics (e.g., magnetic skyrmions) are promising for encoding information bits in future energy-efficient and high-density spintronic devices. Because of antiferromagnetic exchange coupling, skyrmions in ferrimagnetic materials exhibit many advantages in terms of size and efficient manipulation, which allow them to overcome the limitations of ferromagnetic skyrmions. Despite recent progress, ferrimagnetic skyrmions have been observed only in few films in the presence of external fields, while those in ferrimagnetic bulks remain elusive. This study reports on spontaneously generated zero-field ground-state magnetic skyrmions and their subsequent transformation into traditional magnetic bubbles via intermediate states of (bi-)target bubbles during a magnetic anisotropy change in the rare-earth ferrimagnetic crystal DyFe Ti. Spontaneous reversible topological transformation driven by a temperature-induced spin reorientation transition is directly distinguished using Lorentz transmission electron microscopy. The spontaneous generation of magnetic skyrmions and successive topological transformations in ferrimagnetic DyFe Ti are expected to advance the design of topological spin textures with versatile properties and potential applications in rare-earth magnets.
具有纳米尺寸和新颖特性（例如磁 skyrmions）的非平凡手性自旋纹理有望在未来的高能效和高密度自旋电子器件中对信息位进行编码。由于反铁磁交换耦合，铁磁材料中的 skyrmions 在尺寸和高效操控方面具有许多优势，这使其能够克服铁磁 skyrmions 的局限性。尽管最近取得了进展，但在外磁场存在的情况下，仅在少数几种薄膜中观察到铁磁 skyrmions，而在铁磁体中仍然难以捉摸。本研究报告了在稀磁石榴石晶体 DyFeTi 中磁各向异性变化期间，通过（双）目标泡的中间状态，自发产生零场基态磁 skyrmions 及其随后通过中间状态转变为传统磁泡。通过洛伦兹透射电子显微镜直接区分了由温度诱导的自旋再取向跃迁驱动的自发可逆拓扑转变。铁磁 DyFeTi 中磁 skyrmions 的自发产生和连续拓扑转变有望推进具有多种特性的拓扑自旋纹理的设计，并在稀土磁体中具有潜在的应用。
