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.
Dynamic measurement of the thermal stability of the magnetic anisotropy in FeTaN films
In earlier publications it has been shown that the value and direction of the magnetic anisotropy in FeTaN films can be changed by thermal annealing in a dc magnetic field. These films have potential as future write head materials, and this type of instability could pose a problem. In the current work dc and ac annealing experiments have been performed to test the stability of the anisotropy. Our results confirm the model of interstitial-nitrogen-induced anisotropy in the FeTaN films by illustrating that the magnitude of the anisotropy is reduced at higher temperatures, and that the direction of the anisotropy is stable if the time in the switched direction is less than the time required for diffusion of the nitrogen to a different interstitial position. The direction is stable at 100 °C, for square wave magnetic field switching between the easy and hard axes, at frequencies above 500 Hz. The direction is unstable at 100 °C for switching between the hard axes at frequencies less than 5 kHz.
Submicron polymer structures with X-ray lithography and hot embossing
This article describes the process chain for replication of submicron structures with varying aspect ratios (AR) up to 6 in polymethylmethacrylate (PMMA) by hot embossing to show the capability of the entire LIGA process to fabricate structures with these dimensions. Therefore a 4.7 μm thick layer of MicroChem 950k PMMA A11 resist was spin-coated on a 2.3 μm Ti/TiOx membrane. It was patterned with X-ray lithography at the electron storage ring ANKA (2.5 GeV and λc ≈ 0.4 nm) at a dose of 4 kJ/cm3 using a Si3N4 membrane mask with 2 μm thick gold-absorbers. The samples were developed in GG/BDG and resulted in AR of 6–14. Subsequent nickel plating at 52°C resulted in a 200 μm thick nickel tool of 100 mm diameter, which was used to replicate slit-nozzles and columns in PMMA. Closely packed submicron cavities with AR 6 in the nickel shim were filled to 60% during hot embossing.