Transverse elastic-wave absorption due to reversible rotation in a triaxial magnetic material

Abstract

Calculations have been performed on the energy absorption related to rotation of the spontaneous-magnetization vectors due to external shearing sign-varying stresses applied to a multidomain magnetic material, where allowance is made for the magnetic-phase concentrations. The perturbation solution for a system of six equations for the rotational moments is found together with the wave equation to derive the deviations of the magnetization vectors from the easy directions in the stress wave field. The absorption coefficients and internal friction have been derived, together with the defect of the shearing modulus, including the frequency dependence, which are determined via the magnetic, magnetoelastic and elastic constants of the crystal in relation to the orientation of the X′ and Y′ axes of the tensor for the stresses σx′y′ with respect to the 〈100〉 easy axes. When the domain boundaries are fixed, the main contribution to this type of absorption in a ferromagnetic arises from the micro-eddy currents, while in a ferrite, it is due to the spin viscosity and the radiational friction.