Effects Of Defects On The Dynamics Of Antiferromagnetic Skyrmions

Antiferromagnetic skyrmions are promising building block as information carriers for future antiferromagnetic spintronic devices due to their unique properties including zero stray fields,ultrafast dynamics and zero skyrmion Hall effect,which have attracted extensive attention in recent years.In this work,we numerically investigate the effect of two types of defects caused by local variations in perpendicular magnetic anisotropy on the current-induced dynamics of an antiferromagnetic skyrmion.It is found that the skyrmion can be jointly controlled by the driving current and the inhomogeneous magnetic anisotropy in defects.Both types of defects act as pinning sites,which can result in an effective slowdown or even capturing of the antiferromagnetic skyrmion during its motion.We also provide an explanation for the complex behaviors of the antiferromagnetic skyrmion via energy landscape.In particular,there will be a situation where only one skyrmion is outputted when two skyrmions are inputted.This phenomenon could be applied in the transmission,modification and replacement of data in the skyrmion-based racetrack memory as well as in the other skyrmion-based devices.With this in mind,we further propose a new design of logic computing gates based on the manipulation of antiferromagnetic skyrmions,which is numerically realized combining several interactions and phenomena,including the spin Hall effect,voltage-controlled magnetic anisotropy effect,skyrmion-skyrmion interaction and skyrmion-edge interaction.The proposed logic gates can perform the basic Boolean operations of the logic AND,OR,NOT,NAND and NOR gates.It should be noted that the NAND gate is a universal gate and any other logic gates can be implemented by a combination of NAND gates in principle.Our results are useful for the understanding of antiferromagnetic skyrmion physics at low temperatures and could provide guidelines for designing future in-memory logic computing devices with ultra-low energy consumption and ultra-high storage density.