Relationship between microstructure and magnetic properties in soft Fe-Ta-N films

Transverse biased permeability measurements (TBP) were utilized to obtain experimental values of the structure factor using Hoffman´s ripple theory in order to expose the relationship between microstructure and magnetic properties in dc sputtered Fe-Ta-N single layer films with 5.5 a.o.% Ta and varying nitrogen content. The grain size and orientation of the films were obtained by X-ray diffraction and the stress was measured directly. The initial permeability increased from 600 to almost 1700 and the wall coercivity dropped from 5.5 Oe to 1.2 Oe when the structure factor decreased from 0.12 erg/cm² to 0.02 erg/cm². The addition of nitrogen causes a decrease in grain diameter, which is partially responsible for the reduction of the structure factor. The measured structure factor was in reasonable agreement with the value calculated from the film parameters determined experimentally using either the Doyle-Finnegan model or the Takahashi-Shimatsu model for the local anisotropy. Differences between the models are discussed