Strongly Coupled Spin Waves and Surface Acoustic Waves at Room Temperature

TL;DR

This paper demonstrates strong coupling between magnons and surface acoustic waves at room temperature in a tunable on-chip device, revealing potential for advanced magnon-phonon hybrid systems.

Contribution

It introduces a novel on-chip SAW resonator with tunable film thickness for strong magnon-phonon coupling at room temperature, differing from traditional fixed-parameter methods.

Findings

Coupling strength increases monotonically with film thickness.

Strong magnon-phonon coupling observed at room temperature.

Theoretical model agrees with experimental dispersion data.

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. 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.