Separation of heating and magnetoelastic coupling effects in surface-acoustic-wave-enhanced creep of magnetic domain walls

Surface acoustic waves (SAWs) have significant potential for energy-efficient control of magnetic domain walls (DW) owing to the magnetoelastic coupling effect. However, the dissipation of radio frequency (RF) power in a SAW device can result in heating, which can also affect the DW motion. In this work, the heating of a SAW device consisting of a Pt/Co/Ta thin film with perpendicular magnetic anisotropy in between two interdigitated transducers was measured in-situ using an on-chip Pt film as a thermometer within the SAW beampath. The application of SAWs at a center frequency of 48 MHz and a total RF power of 21 dBm resulted in a temperature increase of approximately 10 K within the SAW beam path owing to RF power dissipation. DW velocity in a Pt/Co/Ta thin film was evaluated separately using Kerr microscopy at various temperatures or in the presence of SAWs. With a 10K increase in temperature only, the DW velocity was found to increase from 33±3 µm/s (at room temperature) to 104±8 µm/s under an external magnetic field of 65 Oe. Travelling SAW-assisted DW velocity (116±3 µm/s) is slightly higher than that with a 10 K temperature increase alone, suggesting that the heating plays the major role in promoting DW motion, whereas the DW motion is significantly enhanced (418±8 µm/s) in the presence of standing SAWs indicating that magnetoelastic coupling is more important than heating in this scenario.