Phonon excitation and propagation in thick iron films

Abstract

The generation and propagation of 9.37 GHz sound in polycrystalline iron films ∼13 μm thick is discussed. The excitation is accomplished via the magnetoelastic coupling and is optimized at FMR. No sound absorption dip or exchange asymmetry has been observed in these experiments.

Abnormal expansion during the ferro- to para-magnetic transition in pure iron

“…Meanwhile, the RF field with a frequency of several GHz for ferromagnetic resonance enhances the phonon excitation [13] so that the change in phonon-phonon interaction may cause abnormal expansion near T C . However, because the frequency of the RF field used for the present study is 1 MHz, which is lower than the frequency for ferromagnetic resonance, it is also difficult to explain the abnormal expansion near T C by phonon excitation under the RF field.…”