Dynamical response of vibrating ferromagnets

The resonance frequency of vibrating ferromagnetic reeds in a homogeneous m agnetic field can be substantially modified by intrinsic and extrinsic fiel d-related contributions. Searching for the physical reasons of the field-in duced resonance frequency change and to study the influence of the spin gla ss state on it, we have measured the low-temperature magnetoelastic behavio r and the dynamical response of vibrating amorphous and polycrystalline fer romagnetic ribbons. We show that the magnetoelastic properties depend stron gly on the direction of the applied magnetic field. The influence of the re -entrant spin glass transition on these properties is discussed. We present clear experimental evidence that for applied fields perpendicular to the m ain area of the samples the behavior of ferromagnetic reeds is rather indep endent of the material composition and magnetic state, exhibiting a large d ecrease of the resonance frequency. This effect can be very well explained with a model based on the dynamical response of the reed and the magnetomec hanical pole effect within a domain rotation model and is not related to ma gnetoelasticity. (C) 2000 Elsevier Science B.V. All rights reserved.