Dynamics of magnetic skyrmionium driven by voltage-controlled strain gradients

A magnetic skyrmionium with zero topological number has no skyrmion Hall effect during motion; hence, it has excellent application prospects in racetrack memory. Here, we investigate dynamics of magnetic skyrmionium driven by voltage-controlled in-plane strain gradients via both electromechanical and micromagnetic simulations. It is found that the skyrmionium can be efficiently driven along the direction of the in-plane strain gradients without deflection, that is, the skyrmion Hall angle is zero, and the velocity of skyrmionium can be effectively increased by reducing the magnetic damping constant and increasing the intensity of the strain gradient. Moreover, the driving force and velocity of the skyrmionium increase correspondingly with the increase in size. Most importantly, we demonstrate that the skyrmionium can be efficiently driven by strain gradients under realistic conditions with thermal noise and material inhomogeneity in the ferromagnetic film. The results presented in this study are promising for applications in skyrmionium-based information memory devices.