Realization and Current-Driven Dynamics of Fractional Hopfions and Their Ensembles in a Helimagnet FeGe

3D topological spin textures-hopfions-are predicted in helimagnetic systems but are not experimentally confirmed thus far. By utilizing an external magnetic field and electric current in the present study, 3D topological spin textures are realized, including fractional hopfions with nonzero topological index, in a skyrmion-hosting helimagnet FeGe. Microsecond current pulses are employed to control the dynamics of the expansion and contraction of a bundle composed of a skyrmion and a 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.

Automated summary

3D topological spin textures, called hopfions, have been theoretically predicted but not experimentally confirmed in helimagnetic systems. By using an external magnetic field and electric current, researchers successfully realized the existence of 3D topological spin textures, including fractional hopfions with non-zero topological index, in a skyrmion-hosting helimagnet FeGe. The dynamics of the expansion, contraction, and current-driven Hall motion of a bundle composed of a skyrmion and a fractional hopfion were controlled by microsecond current pulses. This research has demonstrated the novel electromagnetic properties of fractional hopfions and their ensembles in helimagnetic systems.