  The parametric excitation of spin waves by coherent surface acoustic waves is
demonstrated experimentally in metallic magnetic thin film structures. The
involved magnon modes are analyzed with micro-focused Brillouin light
scattering spectroscopy and complementary micromagnetic simulations combined
with analytical modelling are used to determine the origin of the spin-wave
instabilities. Depending on the experimental conditions, we observe spin-wave
instabilities originating from different phonon-magnon and magnon-magnon
scattering processes. Our results demonstrate that an efficient excitation of
high amplitude, strongly nonlinear magnons in metallic ferromagnets is possible
by surface acoustic waves, which opens novel ways to create micro-scaled
nonlinear magnonic systems for logic and data processing that can profit from
the high excitation efficiency of phonons using piezoelectricity.
