Thermal Stability Of FeTaN As A Function Of N And Ta Content
FeTaN thin films promise to be a good candidate for inductive head pole materials. FeTaN thin films which are nanocrystalline and possess the required magnetic properties in the as-deposited state are advantageous because they do not require a high temperature processing anneal. However, FeTaN films must possess sufficient thermal stability in order to maintain their magnetic properties while being processed into inductive heads. In this study we have undertaken systematic microstructural and magnetic measurements on nanocrystalline, single-layer FeTaN thin films as a function of N and Ta content and annealing temperature. The annealing temperatures used are less than 300/spl deg/C and are meant to simulate head processing conditions. The addition of Ta was found to enhance thermal stability. By stabilizing the microstructure, Ta also stabilizes magnetic properties such as coercivity and magnetostriction (structure determines properties). The optimum amount of Ta for thermal stability while maintaining good magnetic properties was 10 weight percent. In the highest N content Fe-10TaN thin films, soft magnetic properties were found to be controlled by the magnetic domain structures which are governed by magnetoelastic anisotropy. These films which exhibited a magnetoelastic anisotropy less than -2/spl times/10/sup 4/ ergs/cm/sup 3/ also exhibited stripe domains which resulted in relatively high coercivities.
A New Type of Magnetic Domain Structure in Negative Magnetostriction Ni-Fe Films
Ni-rich Ni-Fe and Ni evaporated polycrystalline films, the thickness of which is larger than a critical value, were found to be composed of stripe domains running parallel to the field previously applied to the films. B-H loops and magnetoresistance effect revealed that the magnetization in each domain points in one sense and deflects from the plane of the film upwards and downwards alternately. This type of domain structure is to be caused by the anisotropy whose easy axis is normal to the plane of the film, the origin of which is attributed to the magnetostrictive effect due to strains or defects in the film. The width of the domain increases with the thickness of the film, but does not depend sensitively on substrate temperatures and compositions. The critical thickness increases with an elevation of substrate temperatures and with decreasing Ni concentration. The stripe domain is no longer observable for the film containing Ni less than 80% where the magnetostriction constant is positive. The relation...
Search for high moment soft magnetic materials: FeZrN (abstract)
FeN materials exhibiting high moment, low coercivity and small magnetostriction have previously been reported. Zr has been known to reduce the magnetostriction in other Fe alloys. The criteria for an ideal recording head pole material as well as shields for magnetroresistive sensors include high moment, low coercivity, high permeability, and zero magnetostriction. We present here the properties of half micrometer thick rf sputtered FeZrN films on glass coupons. The films were deposited at a pressure of 3 mTorr using a Perkin–Elmer sputtering system. The target was composed of Fe with Zr chips covering approximately 2% of the surface area. The properties were measured as a function of the N2 partial pressure. The saturation magnetization of the as‐sputtered films was approximately 20 kG. The easy axis and the hard axis coercivities show minima at approximately 7%–10% N2 partial pressure of approximately 1.8 and 0.6 G, respectively. The magnetic anisotropy is approximately 5 G yielding a dc permeability of approximately 4000 along the hard axis. X‐ray data reveal a systematic change in the ratio of α‐Fe and γ‐Fe4N; the amount of the γ‐Fe4N phase increases with increasing N2 flow rate. The magnetostriction increases with increasing N2 content crossing zero at approximately 6%. The grain size as probed by atomic force microscopy is an increasing function of the N2 partial pressure, from a few nm for a N2 partial pressure of 5% to as large as 50 nm for a N2 partial pressure of 15%.