Theoretical comparison between skyrmion and skyrmionium motions for spintronics applications

We discuss applications of skyrmioniums to spintronics devices in comparison with the case of skyrmions in this study. It seems that the skyrmioniums are more beneficial than the skyrmions since it is derived from the Thiele equation that the skyrmion Hall effect does not occur in the case of the skyrmioniums. However, we have found that the skyrmioniums have also the disadvantage for the spintronics devices. We cannot utilize the skyrmionium in the system with small Gilbert damping constant since micromagnetic simulation has shown that the skyrmionium structure distorts largely when the Gilbert damping constant is small. From the above reason, the skyrmioniums are not entirely more beneficial to the spintronics devices than the skyrmions. In the last of this paper, we provide a creation method of the skyrmionium by utilizing pulsed magnetic fields. We consider that this method is useful to create the skyrmioniums experimentally.