High-Resolution Scalar/Vector-Field Electron Tomography Unveiling 3D Topological Spin Textures

The emergence of 2D topological spin textures, such as magnetic skyrmions in helimagnets, has garnered significant attention in the field of condensed matter physics and spintronics^1-2. However, our understanding of nontrivial 3D spin textures remains limited, primarily due to the absence of a high-resolution 3D magnetic imaging technique, especially at lower temperatures below room temperature (RT). While some progress has been made in imaging magnetic twisted structures in 3D through nanotomography³, challenges persist in accurately mapping 3D vector fields and achieving the necessary spatial resolution. These obstacles hinder our ability to comprehensively map 3D exotic spin textures in magnets with topological precision over a broad temperature range. The objective of this study is to develop a high-resolution scalar/vector-field electron tomography microscopy technique that covers a wide temperature range from 95 K to RT, enabling real-space observations of various 3D topological spin textures.<br/>In this study, I will introduce scalar/vector-field electron tomography using 3D integrated differential-phase-contrast microscopy and discuss its applications. Specifically, I will show vortex pairs on the surface of elliptical skyrmions in an antiskyrmion-hosting magnet at RT and the formation of 'football'-like skyrmions and their heavy deformations around sample surfaces with varying temperatures in a helimagnet FeGe. This groundbreaking 3D magnetic imaging technique reveals hybrid topological spin textures, including surface spin textures such as vortices and monopoles, providing valuable insights into the topological aspects of various spin textures emerging in topological materials.<br/>*This work was supported by Grants-In-Aid for Scientific Research (Grant No. 19H00660, 23H05431) from the Japan Society for the Promotion of Science and the Japan Science and Technology Agency CREST program (Grant No. JPMJCR1874, JPMJCR20T1).<br/>References<br/>[1] Y. Tokura, and N. Kanazawa, <i>Chem. Rev.</i> 121, 2857 (2021).<br/>[2] N. Nagaosa, and Y. Tokura, <i>Nat. Nanotechnol.</i> 8, 899 (2013).<br/>[3] C. Donnely, <i>et al</i>. <i>Nature</i> 547, 328 (2017); D. Wolf, <i>et al</i>. Nat. Nano. 17, 250 (2022).