In-situ observation of magnetic vortices and their manipulation by external fields in Tb(Co_1−xFe_x)₅ ribbons

Nontrivial spin textures including magnetic vortices, skyrmions, and merons possess intriguing properties that are suitable for the application in further spintronics devices. The stability of topological spin textures in a broad temperature span is imperative for their potential applications as information carriers. In this study, we show the in-situ observation of the magnetic domain configuration and their manipulation under temperature and in-plane magnetic field in amorphous or nanocrystalline Tb(Co_1−xFe_x)₅ (x = 0.5, 0.8, 1.0) ribbons using Lorentz transmission electron microscopy. The results demonstrate that the formation of magnetic vortices is highly dependent on the degree of amorphization of Tb(Co_1−xFe_x)₅ ribbons and intrinsic magnetic parameters, which can be controlled by the composition. The higher the Fe content, the stronger the degree of amorphous in Tb(Co_1−xFe_x)₅ ribbons. Whereby, high-density magnetic vortices develop inside domain walls in the TbFe₅ ribbon. Moreover, no matter how the degree of amorphization changes, magnetic domain structures including vortices in these ribbons have good thermal stability in the temperature range of 120–300 K, while the evolution of magnetic domains under the application of magnetic field is greatly affected by the degree of amorphization. The cross-tie domain walls consisted of magnetic vortices and antivortices form as applying a proper magnetic field in TbFe₅, in contrast with the unchanged magnetic domains in Tb(Co_0.5Fe_0.5)₅. This study provides a guideline for the design of magnetic vortex materials and soft magnetic materials.