Controllable arrangement of magnetic skyrmions by strain regulation

The efficient manipulation of magnetic skyrmions is crucial for the development of future spintronic devices. Here, we demonstrate the controllable arrangement of magnetic skyrmions through strain regulation in the bilayer film system composed of piezoelectric and ferromagnetic layers. The motion characteristics and energy distribution of skyrmions in the ferromagnetic layer under an in-plane periodic strain with a sinusoidal shape are investigated by using a phase-field model. It is found that the final equilibrium location of the skyrmion with the lowest total energy has the maximum positive strain and a zero strain gradient. Furthermore, the periodic strain transforms the disordered multi-skyrmions to an ordered skyrmion array at the desired positions by adjusting the wavelength and amplitude of the strain. Based on the controllability of the skyrmion position, the temperature gradient perpendicular to the strain leads to the directional motion of multi-skyrmions along the desired track. The controllable directional motion of skyrmions by strain regulation proposed in this work is promising for application in the racetrack memory and neuromorphic computing devices.