Strongly Coupled Spin Waves and Surface Acoustic Waves at Room Temperature
Yunyoung Hwang, Jorge Puebla, Kouta Kondou, Carlos Gonzalez-Ballestero, Hironari Isshiki, Carlos Sánchez Muñoz, Liyang Liao, Fa Chen, Wei Luo, Sadamichi Maekawa, Y. Otani
Abstract
Here, we report the observation of strong coupling between magnons and surface acoustic wave (SAW) phonons in a thin CoFeB film constructed in an on-chip SAW resonator by analyzing SAW phonon dispersion anticrossings. We employ a nanostructured SAW resonator design that, in contrast to conventional SAW resonators, allows us to enhance shear-horizontal strain. Crucially, this type of strain couples strongly to magnons. Our device design provides the tunability of the film thickness with a fixed phonon wavelength, which is a departure from the conventional approach in strong magnon-phonon coupling research. We detect a monotonic increase in the coupling strength by expanding the film thickness, which agrees with our theoretical model. Our work offers a significant way to advance fundamental research and the development of devices based on magnon-phonon hybrid quasiparticles.