The dependence of the velocity of surface acoustic waves (SAWs) as a function of an external applied magnetic field is investigated in a $\mathrm{Fe}$ thin film epitaxially grown on a piezoelectric $\mathrm{Ga}\mathrm{As}$ substrate. The SAW velocity is observed to strongly depend on both the amplitude and direction of the magnetic field. To interpret the experimental data a phenomenological approach to the relative change in SAW velocity is implemented. We find that the experimental velocity variation can be well reproduced provided that the spin-wave dispersion is taken into account. The validity of this phenomenological model is attested by the comparison with a fully magnetoelastic one. Nonreciprocity of SAW velocity is also addressed both experimentally and theoretically.

• Received 28 March 2022
• Revised 2 November 2022
• Accepted 9 November 2022

DOI:https://doi.org/10.1103/PhysRevApplied.18.064043