We report a strong coupling between a Love surface acoustic wave (SAW) and a spin wave in epitaxial FeRh as analyzed from their anticrossing dispersion relationships obtained by Brillouin light scattering. Reproducing the results using a numerical model that solves the coupled Landau-Lifshitz and Christoffel equations reveals that this effect stems from both the large magnetoelastic coupling coefficient in this material, $|B_2|$ = $17\mathrm{MJ}{\mathrm{m}}^{-3}$, and the strength of the Love-wave magnetoacoustic effective field when the magnetization vector $\mathbf{M}$ is parallel to the SAW wave vector $\mathbf{k}$. We also observe a substantial, albeit weaker, coupling in the unusual configuration of the Sezawa surface wave crossing the pseudo Damon-Eshbach mode, i.e., when the angle between M and k is $\pi /4$. These findings identify the optimal acoustic modes and magnetic geometries for achieving strong phonon–magnon hybridization, paving the way for coherent information transfer via elastic waves in magnetoacoustic nanodevices.

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• Acoustic wave phenomena
• Brillouin scattering & spectroscopy
• First order phase transitions
• Magnetism
• Magnetoelastic effect
• Magnetostriction
• Thin films
• Ferromagnetic resonance
• Magnetization measurements
• Spin wave spectroscopy