Transformation from antiferromagnetic target skyrmion to antiferromagnetic skyrmion by unzipping process through a confined nanostructure.

The manipulation of magnetic skyrmion has been attracting considerable attention for the fundamental physical perspective and promising applications in spintronics, ascribed to their nontrivial topology and emergent electrodynamics. However, there is a hindrance to the transmission of a skyrmion in the racetrack memory due to the skyrmion Hall effect (SHE). Antiferromagnetic (AFM) materials provide a possibility to overcome the SHE in high-velocity data writing. Herein, we systematically investigate the generation and motion of an AFM target skyrmion under the spin-polarized current. We found that the AFM target skyrmion can reach a velocity of 1088.4 m s-1under the current density of 8 × 1012 A m-2, which is lower than 1269.8 m s-1for the AFM skyrmion. This slowdown can be ascribed to the deformation of AFM target skyrmion in the process of motion on a nanotrack. In addition, we observed a transformation from AFM target skyrmion to AFM skyrmion by the unzipping process through a constricted nanostructure which is mediated by the formation of AFM domain wall. Two energy barriers need to be overcome in this dynamic process, i.e. 2.93 × 104 eV from AFM target skyrmion to AFM domain wall, and 7.625 × 103 eV from AFM domain wall to AFM skyrmion. Our results provide guidance for future target skyrmion-based devices.