Micromagnetic dynamics of a skyrmionium diode in a nanotrack

Magnetic Skyrmionium or Donut skyrmion are unique magnetic spin textures that show promise for future memory and logic technologies. Unlike regular skyrmions, they do not experience Skyrmion Hall Effect (SkHE), making them more stable and easier to glide in nanotrack. In this study, we use micromagnetic simulation to investigate the motion of skyrmionium, when a spin-polarized current is applied along the x-direction using the Spin-Transfer Torque (STT). We report the dependence of skyrmionium dynamics on the geometry of the track. In symmetric track, skyrmionium moves in both directions, whereas in asymmetric track, it moves in one direction while getting blocked in the other, similar to semiconductor diode effect. This shows the possibility of building a skyrmionium diode with a velocity of 75–100 m/s. We validate the dynamics using a modified Thiele equation to support the simulation results. In addition to current-driven dynamics, we have also examined the response of skyrmionium motion to spin wave excitations. By applying an oscillating magnetic field with different frequencies, we have observed a strong frequency dependence in the motion, including enhancements in velocity at specific frequencies. This suggests that resonant conditions can enhance controlled skyrmionium motion, opening up new ways to tune their behaviour. We have studied the dependence and effective control of skyrmionium motion on different parameters.