Current-induced dynamics of isolated antiferromagnetic antiskyrmion and antiskyrmionium

Abstract

Topologically stable spin structures known as magnetic antiskyrmions spontaneously emerge in magnets with broken in-plane rotation symmetry when current is injected. While many studies have focused on their behaviors in ferromagnetic (FM) materials, limited attention has been paid to antiskyrmions in their antiferromagnetic (AFM) counterparts. In spintronic applications, the Magnus force of an AFM antiskyrmion cancels out completely due to its comparable but opposite sign spin pattern on the A and B sublattices in the AFM bipartite system, while an FM antiskyrmion exhibits transverse motion when driven by the currents, causing limitations to antiskyrmion motion velocity and information loss when the antiskyrmion is annihilated at the edges of racetracks. Here, we report the nucleation and dynamics of an isolated AFM antiskyrmion and antiskyrmionium induced by current analytically and numerically. We demonstrate how AFM antiskyrmions and antiskyrmioniums are stabilized and manipulated with the same velocity by spin transfer torques and with different velocities by spin-orbit torques. Under suitable conditions, the AFM antiskyrmion and antiskyrmionium can be driven at velocities as high as 6 km/s without the skyrmion Hall effect, far greater than their ferromagnetic counterparts. Furthermore, the critical driving current density of the AFM antiskyrmion (antiskyrmionium) is much larger than that of the FM antiskyrmion (antiskyrmionium). Our results contribute to the development of antiferromagnetic antiskyrmions and antiskyrmioniums by shedding light on their stabilization and dynamics.