Fluctuation of stripe domains mediated by topological magnetic

Abstract

The magnetic stripe domains observed in the vicinity of the spin reorientation transition is a great platform for the study of dynamical behaviors of various topological magnetic states as the domain wall structures include defect spin structures such as magnetic skyrmions [1] and magnetic dislocations [2,3] and those rich variations of topological magnetic defects are strongly associated with the domain motions. In analogy to the edge dislocations in the crystal lattice [4], the presence of the magnetic dislocations plays a crucial role to facilitate the deformation in the overall structure of the stripe domains when they are densely crowded and topologically separated. Although studying the magnetic defects and their roles in the stripe domain phase is highly demanded from both scientific and technological perspectives, only few experimental works have been reported so far. In the present work, we directly observed the fluctuations of stripe domains as well as the severance and reconnection of the stripe domains mediated by the motion of the topological defects. Using the full-field transmission soft X-ray microscope (XM-1) [5], a few hundred nm-sized magnetic defects created in ferrimagnetic systems are identified as shown in Fig. 1. To align the direction of the stripe axis, in-plane magnetic field was applied and the external perturbations driven by magnetic fields combined with current pulses are given to trigger the movement of the magnetic dislocations. It is found that the magnetic dislocations not only propagate along the direction of the stripe domains but also move perpendicular to the stripe domain by transferring its topology. The motions of dislocations result in a collective drift of stripe domain pattern over the mesoscopic length scales. Ad itionally, pair annihilation of magnetic dislocations and the motions of bubble skyrmions mediated by magnetic dislocations are also clearly observed.