Excitation of Ferromagnetic Resonance Using Surface Acoustic Waves

Mechanical rotation of a crystal lattice in ferromagnetic materials can be energetically coupled with its magnetization via magnetoelastic coupling or spin rotation coupling. Surface acoustic wave (SAW) in piezoelectric materials is one of the promising candidates to realize the mechanical excitation of magnetization dynamics. In order to understand the mechanical rotation induced magnetization dynamics quantitatively, we examined the ferromagnetic resonance in an Ni film using a SAW in a LiNbO₃ substrate. By decreasing a period of interdigital transducer as short as 4 μm which is one-fifth of the previous work by Weiler [M. Weiler and co-workers, Elastically driven ferromagnetic resonance in Nickel thin films. Phys Rev Lett 106, 117601 (2011)], the fundamental frequency of SAW could be higher than 800 MHz. From the dependence of microwave absorption on the angle between the magnetization and the wave vector of SAW, it was confirmed that the Rayleigh type SAW, which was significant to obtain a large mechanical coupling with the magnetization, was dominantly excited in the 800-MHz-SAW device.