Realization and current-driven dynamics of fractional hopfions and their ensembles in a helimagnet FeGe.

Three-dimensional (3D) topological spin textures-hopfions-have been predicted in helimagnetic systems but have not been experimentally confirmed thus far. By utilizing external magnetic field and electric current in the present study, 3D topological spin textures were realized, including fractional hopfions with nonzero topological index, in a skyrmion-hosting helimagnet FeGe. Microsecond current pulses were employed to control the dynamics of the expansion and contraction of a bundle composed of a skyrmion and fractional hopfion, as well as its current-driven Hall motion. This research approach has demonstrated the novel electromagnetic properties of fractional hopfions and their ensembles in helimagnetic systems. This article is protected by copyright. All rights reserved.