Phonon generation by ferromagnetic resonance in thin films

The longitudinal and transverse phonon generation by ferromagnetic resonance in a thin film, which is subjected to both spin-pinned and spin-unpinned boundary conditions, is calculated. An arbitrary acoustic-impedance condition at the film surface which is bonded to a nonmagnetic rod is used. The spin-unpinned case gives more power transmitted into the rod than the spin-pinned case under otherwise optimized conditions. In addition the optimum acoustic impedance of the rod for maximum power transmission is much smaller than the impedance of the film.