Impact of Spin-Wave Dispersion on Surface-Acoustic-Wave Velocity

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