SEARCH FOR HIGH MOMENT SOFT-MAGNETIC MATERIALS - FEZRN

FeN materials exhibiting high moment, law coercivity and small magneto striction have-previously been reported. Zr has been known to reduce t he magnetostriction in other Fe alloys. The criteria for an ideal reco rding head pole material as well as shields for magnetoresistive senso rs include high moment, low coercivity, high permeability, and zero ma gnetostriction. We present here the properties of 0.3 mu m thick rf sp uttered FeZrN films measured as a function of the N-2 partial pressure . The films were deposited at a pressure of 3 mT using a Perkin Elmer sputtering system. The target was composed of Fe with Zr chips coverin g approximately 2% of the surface area. The easy axis and hard axis co ercivities show minima of 1.8 and 0.6 Oe, respectively, at 7-10 % N-2 partial pressure with a saturation magnetization of about 18 kG. The m agnetic anisotropy field is approximately 5 Oe yielding a de permeabil ity of approximately 4000 along the hard axis. X-ray data reveal a sys tematic change in the ratio of alpha-Fe and gamma-Fe-4, N; the amount of the gamma-Fe4N phase increasing with increasing N-2 partial pressur e. The magnetostriction increases with increasing N-2 content crossing zero at approximately 6%. The grain size, as probed by atomic force m icroscopy, is an increasing function of the N-2 partial pressure; from a few nm for N-2 partial pressures of 5% to being as large as 50 nm f or a partial pressure of 15%. The surface roughness is about 1 nm. (C) 1996 American Institute of Physics.