Topological Spin Textures in Three Dimensions

Chiral magnets are a series of magnets with broken inversion symmetry. A new type of spin interaction therein, the Dzyaloshinskii-Moriya interaction, stimulates the formation of many novel topological spin textures. One important example is the emergence of magnetic skyrmion, whose nontrivial topology enables unique dynamical property and thermal stability, and gives rise to promising applications in future spintronic devices. However, skyrmion is just a two-dimensional texture. Its three-dimensional (3D) counterparts are widely unexplored. In this talk, I will discuss realization of 3D skyrmionic textures, including target skyrmion¹, skyrmion bundle², and skyrmionic vortices³. I will also discuss the magnetic hopfion, a rigorously defined 3D topological texture. We propose the presence of zero-field hopfion in synthetic chiral magnetic multilayers⁴. All these 3D textures exhibit novel dynamical properties that can be formulated in terms of collective coordinates⁵. These works could stimulate the development of 3D spintronics.

References: 

¹F. Zheng, H. Li, S. Wang, D. Song, C. Jin, W. Wei, A. Kovacs, J. Zang, M. Tian, Y. Zhang, H. Du, and R. E. Dunin-Borkowski, Physical Review Letters 119, 197205 (2017). 

²J. Tang, Y. Wu, W. Wang, L. Kong, B. Lv, W. Wei, J. Zang, M. Tian, and H. Du, Nature Nanotechnology (2021) in press.

³K. Niitsu, Y. Liu, A. C. Booth, X. Z. Yu, N. Mathur, M. J. Stolt, D. Shindo, S. Jin, J. Zang, N. Nagaosa, and Y. Tokura, Nature Materials (2021) in press.

⁴Y. Liu, R. K. Lake, J. Zang, Physical Review B 98, 174437 (2018).

⁵Y. Liu, W. T. Hou, X. F. Han, and J. Zang, Physical Review Letters 124, 127204 (2020).