Generation of exchange magnons in thin ferromagnetic films by ultrashort acoustic pulses
arXiv:1910.09481 · doi:10.1016/j.jmmm.2019.166320
Abstract
We investigate generation of exchange magnons by ultrashort, picosecond acoustic pulses propagating through ferromagnetic thin films. Using the Landau-Lifshitz-Gilbert equations we derive the dispersion relation for exchange magnons for an external magnetic field tilted with respect to the film normal. Decomposing the solution in a series of standing spin wave modes, we derive a system of ordinary differential equations and driven harmonic oscillator equations describing the dynamics of individual magnon mode. The external magnetoelastic driving force is given by the time-dependent spatial Fourier components of acoustic strain pulses inside the layer. Dependencies of the magnon excitation efficiencies on the duration of the acoustic pulses and the external magnetic field highlight the role of acoustic bandwidth and phonon-magnon phase matching. Our simulations for ferromagnetic nickel evidence the possibility of ultrafast magneto-acoustic excitation of exchange magnons within the bandwidth of acoustic pulses in thin samples under conditions readily obtained in femtosecond pump-probe experiments.
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Cited by in corpus (8)
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- Nondestructive femtosecond laser lithography of Ni nanocavities by controlled thermo-mechanical spallation at the nanoscale
- Anatomy of ultrafast quantitative magneto-acoustics in freestanding nickel thin films
- Atomistic simulations of magnetoelastic effects on sound velocity
- Excitation of high-frequency magnon modes in magnetoelastic films by short strain pulses
- Efficient ultrafast photoacoustic transduction on Tantalum thin films
- Resonant phonon-magnon interactions in free-standing metal-ferromagnet multilayer structures
- Ultra-high frequency magnetic resonance through strain-spin coupling in perpendicular magnetic multi-layers