Katmis Ferhat, Lauter Valeria, Yagan Rawana, Brandt Iuri S, Cheghabouri Arash M, Zhou Hua, Freeland John W, de Araujo Clodoaldo I L, Jamer Michelle E, Heiman Don, Onbasli Mehmet C, Moodera Jagadeesh S
Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
Francis Bitter Magnet Laboratory & Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
Adv Mater. 2025 Aug 18:e11754. doi: 10.1002/adma.202511754.
Topological spin configurations, such as soliton-like spin texture and Dirac electron assemblies, have recently emerged in fundamental science and technology. Achieving stable topological spin textures at room temperature is crucial for their use as long-range information carriers. However, their creation and manipulation are hindered by multi-step field training and competing interactions. Thus, a spontaneous ground state for multidimensional topological spin textures is desirable, with skyrmions forming swirling, hedgehog-like spin structures in two dimensions and hopfions as their twisted 3D counterparts. Here, the first observation of robust and reproducible topological spin textures of hopfions and skyrmions observed at room temperature and in zero magnetic field is reported, which are stabilized by geometric confinement and protected by interfacial magnetism in a ferromagnet/topological insulator/ferromagnet trilayer heterostructure. These skyrmion-hopfion configurations are directly observed at room temperature with Lorenz transmission electron microscopy. Using micromagnetic modeling, the experimental observations of hopfion-skyrmion assemblies are reproduced. This model reveals a complete picture of how spontaneously organized skyrmion lattices encircled by hopfion rings are controlled by surface electrons, uniaxial anisotropy, and Dzyaloshinskii-Moriya interaction. This study provides evidence that topological chiral spin textures can facilitate the development of magnetic topological carriers, paving the way for ultralow-power and high-density information processing.
拓扑自旋构型，如类孤子自旋纹理和狄拉克电子集合体，最近在基础科学和技术领域崭露头角。在室温下实现稳定的拓扑自旋纹理对于将其用作长程信息载体至关重要。然而，它们的产生和操控受到多步场训练和竞争相互作用的阻碍。因此，多维拓扑自旋纹理的自发基态是理想的，其中斯格明子在二维中形成漩涡状、刺猬状的自旋结构，而霍普费子则是其扭曲的三维对应物。在此，报道了在室温及零磁场下首次观察到的稳健且可重复的霍普费子和斯格明子拓扑自旋纹理，它们在铁磁体/拓扑绝缘体/铁磁体三层异质结构中通过几何限制得以稳定，并由界面磁性保护。这些斯格明子 - 霍普费子构型在室温下通过洛伦兹透射电子显微镜直接观察到。利用微磁学建模，再现了霍普费子 - 斯格明子集合体的实验观测结果。该模型揭示了由霍普费子环环绕的自发组织的斯格明子晶格如何受表面电子、单轴各向异性和兹亚罗申斯基 - 莫利亚相互作用控制的全貌。这项研究提供了证据，表明拓扑手性自旋纹理可以促进磁性拓扑载体的发展，为超低功耗和高密度信息处理铺平了道路。
