Fully Resonant Magneto-elastic Spinwave Excitation by Surface Acoustic Waves under Conservation of Energy and Linear Momentum

We report on the excitation of spin waves in micro-structured magnetic thin films by surface acoustic waves (SAWs). The spin waves as well as the acoustic waves are studied by micro-focused Brillouin light scattering spectroscopy. Besides the excitation of the ferromagnetic resonance, a process which does not fulfil momentum conservation, the excitation of finite-wavelength spin waves can be observed at low magnetic fields. By conducting micromagnetic simulations we verify that during this excitation both energy and linear momentum are conserved and fully transferred from the SAW to the spin wave.