  Surface acoustic waves (SAWs) have emerged as innovative and energy-efficient
means to manipulate domain walls (DWs) and skyrmions in thin films with
perpendicular magnetic anisotropy (PMA) owing to the magnetoelastic coupling
effect. This thesis focuses on the complex interplay between SAWs and magnetic
thin films. The effects of the standing SAWs on the magnetisation dynamics in a
Ta/Pt/Co/Ir/Ta thin film with PMA were first investigated. SAWs with frequency
of 93.35 MHz significantly reduced the coercivity of the thin film by 21% and
enhanced the magnetisation reversal speed by 11-fold. Standing SAWs introduce a
dynamic energy landscape with a unique spatial distribution, forming striped
domain patterns in the thin film. The use of rf signals for generating SAWs
inevitably causes a heating effect in the device. This heating effect was
examined in situ in a SAW device featuring a Ta/Pt/Co/Ta thin film with PMA
using an on-chip platinum thermometer. The temperature increased by 10 K in the
presence of SAWs at centre frequency of 48 MHz. The DW velocity was
significantly enhanced in the presence of the standing SAWs by a factor of 4
compared to that with temperature change alone owing to the magnetoelastic
coupling effect. To understand the SAW-enhanced DW motion, comprehensive
micromagnetic simulations were performed on thin films in the presence of
travelling SAWs. The findings highlighted that SAW-induced vertical Bloch lines
within DWs can simultaneously boost DW depinning and dissipate energy at the DW
via spin rotation. The SAW-induced strain gradient can be exploited to control
skyrmion motion in a current-free manner. Micromagnetic simulations revealed
that the use of orthogonal SAWs, combining horizontal travelling and vertical
standing waves, offered a promising approach to direct skyrmion motion along
desired trajectories, avoiding undesirable Hall-like motion.
