Enhanced domain wall motion by surface acoustic waves

Domain walls (DWs) in thin films with perpendicular magnetic anisotropy (PMA) are promising information carriers for the next generation of data storage and logic operation devices.^{[1, 2]} However, controlling DW motion efficiently remains unsolved. Here, we performed micromagnetic simulations (Mumax3) demonstrating an enhanced DW velocity in a PMA film using dynamic strain introduced by travelling surface acoustic waves (SAWs) within the creep regime. Pinning sites were created by introducing anisotropy disorder (1% and 3%). The results show that the DW velocity decreases as the SAW frequency increases from 50 to 200 MHz in the thin film with lower anisotropy disorder (1%). On the contrary, DW velocity increases with the increasing SAW frequency for the thin film with a higher anisotropy disorder of 3%. The dynamic strain waves create a dynamic energy landscape and introduce spin rotation. The period of the SAW-induced spin rotation depends on the SAW frequency. The spin rotation, on the one hand, enhances the possibility of the domain depinning from the pinning sites (for higher anisotropy disorder); on the other hand, also causes energy wastage (for lower anisotropy disorder).