Realization and current-driven dynamics of fractional hopfion and its ensembles in a helimagnet

Abstract The three-dimensional (3D) topological spin textures – hopfions – were predicted in the helimagnetic systems but have not been experimentally confirmed thus far. This study utilized external magnetic field and electric current to realize 3D topological spin textures including fractional hopfions with nonzero topological index in the skyrmion-hosting helimagnet FeGe. Microsecond current pulses and in-plane magnetic field were employed to control the dynamics of the expansion and contraction of the bundle composed of skyrmion and fractional hopfion as well as the current-driven Hall motion of the bundle. The present results demonstrate how to manipulate and control 3D topological objects such as hopfion and its bound state in helimagnetic systems.