3D Topological Solitons and Their Dynamics

The three-dimensional (3D) topological solitons – hopfions [1]– were predicted in the chiral-lattice magnets [2] but have not been experimentally confirmed thus far. By utilizing the external magnetic field and electric current, the fractional hopfions with nonzero topological charge and their ensembles can be excited at lower temperatures ~ 100 K far from <i>T</i>_C (~ 278 K) [3] in a chiral-lattice magnet FeGe, in which 2D topological soliton lattice - skyrmion lattice - are thermodynamically stable near <i>T</i>_C [3]. Microsecond current pulses and in-plane magnetic field were employed to control dynamics of the expansion and contraction of the bundle of skyrmion and fractional hopfion, as well as its current-driven Hall motion [4]. The present work demonstrates how to manipulate and control 3D topological objects such as hopfion and its bound state in magnets.<br/>In this talk, I will also present other topological solitons like merons, bimerons, and their current-driven dynamics in the FeGe with the Co-dopant.<br/>*This work was supported in part by Grants-In-Aid for Scientific Research (A) (Grant No. 19H00660) from the Japan Society for the Promotion of Science (JSPS) and the Japan Science and Technology Agency (JST) CREST program (Grant No. JPMJCR1874, JPMJCR20T1), Japan.<br/><br/>J. B. Tai and I. I. Smalyukh, <i>Science </i>365, 1449 (2019).<br/>[2] R. Voinescu, J. B. Tai and I. I. Smalyukh, <i>Phys. Rev. Lett. </i>125, 057201 (2018)<br/>Y. Tokura, and N. Kanazawa, <i>Chem. Rev.</i> 121, 2857 (2021).<br/>[4] X. Z. Yu, <i>et al. </i>submitted (2022), DOI: 10.21203/rs.3.rs-2026691/v1