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.
Magnetic properties and crystal structure of high moment FeTaN materials for thin‐film recording heads
High‐power density, high growth rate dc magnetron reactive sputtering has been used to grow single‐layer FeTaN films. Ta has been found effective in improving the soft magnetic properties as well as the thermal stability of FeN films. For films containing ∼1.6 a/o Ta prepared under sputtering conditions of pN2/pAr=0.06, a power density of 2.5 or 3.9 W/cm2 and vacuum post‐annealed at 350 °C for 1 h, the following properties are observed: saturation magnetization (Ms) values of ∼1550 emu/cc, coercivity (Hc) of ∼1 Oe, permeability of 1700–2300 at 20 MHz, and anisotropy field of ∼7 Oe. XRD scans yielded peaks characteristic of a random polycrystalline single phase bcc structure.
Theoretical study of magnetostriction in FeTaN thin films
Single layer films of FeTaN have been deposited by dc magnetron sputtering, and the relationships between the magnetostriction and film composition have been studied. A linear increase in magnetostriction with nitrogen content has been explained by the dependence of λ100 on nitrogen concentration. The form of this dependence has been derived based on a theory developed by De Vries for describing the magnetic after effect in iron films with interstitial nitrogen. At room temperature, the best fit for the experimental magnetostriction data was found for an interstitial interaction constant of D=4.18×106 J/m3. The total magnetic anisotropy energy per grain, U110, has also been calculated as a function of the strain for FeN films with a (110) orientation under a tetragonal deformation. This calculation used the results derived for the dependence of the magnetostriction constant, λ100, on nitrogen concentration. The calculated U110 value shows a minimum at a lattice strain value of e11=0.0029, in close agreeme...