A research team from the High Magnetic Field Laboratory of the Hefei Institutes of Physical Science of the Chinese Academy of Sciences, together with collaborators from Anhui University, ShanghaiTech University, and the University of New Hampshire, has demonstrated the first electrically controllable generation of hopfions—three-dimensional topological solitons—in a solid-state magnetic system. The results are published online in Nature Materials.

Proposed in 1975, hopfions are three-dimensional topological structures characterized by a Hopf charge and capable of forming rings, links, and knots. Although they are predicted to exist in a wide range of physical systems—from magnetic materials and plasmas to the early universe—their complexity has kept hopfions largely confined to theory, with only limited experimental realization and control.

In this study, the researchers used a chiral magnet as a laboratory test bed. By applying spin-transfer torque together with thermal excitation, they successfully generated magnetic hopfions in the chiral magnet FeGe.