A contribution from the magnetoelastic effect to measured microwave permeability of thin ferromagnetic films

Microwave magnetic performance of thin ferromagnetic films is of interest in view of many technical problems. For measuring the microwave permeability, a shorted stripline technique is in common use. Recently, a coaxial technique has been developed for permeability measurements of films deposited onto a flexible substrate. The coaxial technique is reported to be advantageous over the conventional stripline method in wideband operating range and accuracy. In this paper, measurement results are presented which are obtained with these two techniques for Fe–N films. It is found that the magnetoelastic effect contributes greatly to the measured microwave permeability of the films. With the coaxial measurements under an external magnetic bias, this effect may be accounted for to estimate the permeability of a plane film sample. Additional information on the properties of the film can also be extracted from these data, such as estimations of average magnetic anisotropy field and of the magnetostriction constant of the film.