Anatomy of ultrafast quantitative magnetoacoustics in freestanding nickel thin films

We revisit the quantitative analysis of ultrafast magneto-acoustic experiment in a freestanding nickel thin film by Kim and Bigot [1] applying our recently proposed approach magnetic acoustic eigenmodes decomposition Vernik et al. [2]. show that application modeling to time-resolved reflectivity measurements allows for determination amplitudes lifetimes standing perpendicular phonon resonances with unprecedented accuracy. The damping is found scale as $\propto\omega^2$ frequencies up 80~GHz peak reach $10^{-3}$. experimentally measured magnetization dynamics different orientations an external field agrees well numerical solutions magneto-elastically driven magnon harmonic oscillators. Symmetry-based selection rules magnon-phonon interactions predicted allow unambiguous discrimination between spatially uniform non-uniform modes, confirmed comparing resonantly enhanced magneto-elastic simultaneously on opposite sides film. Moreover, separation time scales (early) rising (late) decreasing precession provide access (Gilbert) parameters single measurement.