Neutron diffraction and ferromagnetic resonance studies on plasma-sprayed MnZn ferrite films

Abstract

The magnetic properties of MnZn ferrites are affected by the plasma spray process. It is found that

improvements can be made by annealing the ferrite films at 500 °C–800 °C. The annealing induced

magnetic property changes are studied by neutron diffraction and ferromagnetic resonance

techniques. The increase of the saturation magnetization is attributed to the cation ordering within

the spinel lattice, which increases the magnetic moment per ferrite formula. The refinements on the

neutron diffraction data suggest that the redistribution of the cation during annealing neither starts

from a fully disordered state nor ends to a fully ordered state. The decrease of the coercivity is

analyzed with the domain wall pinning model. The measurements on the magnetostriction and

residual stress indicate that coercive mechanisms arising from the magnetoelastic energy term are

not dominant in these ferrite films. The decrease of the coercivity for annealed ferrite films is mainly

attributed to the decrease of the effective anisotropic field, which may result from the

homogenization of the film composition and the reduction of the microstructural discontinuity (e.g.,

cracks, voids, and splat boundaries).