Interaction of a Magnetic Skyrmionium With an Engineered Defect

High mobility and the absence of the skyrmion Hall effect are demonstrated in a magnetic skyrmionium, which consists of two skyrmions with opposite topological charges. Despite these advantages, material defects have the potential to alter the skyrmionium's dynamics. In this report, we investigate the motion of a skyrmionium driven by a current on a racetrack containing an engineered cylindrical defect. Our model demonstrates three possible outcomes of the interaction between the skyrmionium and the defect, depending on the applied current density: pinning, transformation, and transmission. Pinning takes place when the driving force generated by the current is inadequate to counteract the repulsive force at the defect boundary, causing the skyrmionium to become entrapped. Transformation happens inside the defect, where the skyrmionium might convert into a skyrmion due to the higher effective field resulting from the change in film thickness. Transmission takes place when the force exerted by the applied current significantly exceeds the repulsive force at the defect boundary, leading to minimal impact on the skyrmionium motion. These results offer significant understanding of skyrmionium behavior when interacting with engineered defects and present potential implications for the development of novel skyrmionic devices.