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We have fabricated ferromagnet-insulator-ferromagnet tunnel junctions with Co and NiFe electrodes, where the Co electrodes are pinned with a hard magnetic Co81Pt19 alloy layer. This approach gives a coercivity of about 300 Oe for the Co layer, while that of the NiFe is about 80 Oe, so we obtain antiparallel magnetization over a wide field range. The Al2O3 tunneling barrier layers were formed by in situ plasma oxidation of elemental Al layers with thicknesses from 10 to 25 Å. For the junctions, we find room temperature magnetoresistance ratios as high as 13% and nonlinear current–voltage curves that are well fit by the Simmons tunneling theory. Depth profiling x-ray photoelectron spectroscopy of oxidized Al barrier layers on Co underlayers reveals a stoichiometry of nearly Al2O3.

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We have found that the soft magnetic properties of FeN/AlN laminated films do not degrade on sloping surfaces. The easy axis coercivities of FeN/AlN multilayer films are approximately 1.5 Oe and have little variation with slope angle, α. The anisotropy fields slightly vary from 13 to 17 Oe when the slope angles (α) change from 0° to 60°. In contrast, single layer FeN films show a significant degradation of soft magnetic properties with the slope angle. Residual stress does not have a significant correlation with magnetic properties. The large coercivities and saturation fields in the single layer FeN films can be ascribed to a change in the (110) texture of the films.

High crystalline quality thick GaN films were grown by vapor phase epitaxy using GaC13 and NH 3. The growth rate was in the range of 10 ~ 15 ~m/h. GaN films grown at higher temperatures (960~ 1020 ~ were single crystalline with smooth surface morphologies. No chlorine impurity was incorporated in these films during growth. The best crystalline quality and surface morphology of grown films was achieved by sputtering a thin A1N buffer layer, prior to growth. According to reflection high energy electron diffraction and atomic force microscopy measurements, as-sputtered AlN buffer layer was amorphous with root means square roughness of 0.395 nm and then crystallized during the GaN growth. This improved the GaN growth due to more uniform distribution of GaN nucleation. Rutherford backscattering channeling experiments produced the lowest value from the GaN film grown on a-AlzO 3 with a 500/k A1N buffer layer at 1020~

Abstruct -The magnetic effects of a saturable magnetic keeper layer on the peak amplitude and shape of isolated readback pulses from longitudinal thin film media were modeled as 2-dimensional magnetostatic field interactions using the boundary element method. The model assumes a standard thin film head and fly height of a 50% slider, a saturable NiFe keeper, and a perfectly sharp recorded transition in highcapacity longitudinal thin film media.Isolated pulses calculated from the model show that the keeper increases the peak amplitude(55%), decreases the half-height pulse width(46%), introduces pulse shape asymmetry, and eliminates undershoots from pole edges. The pulse shape is found to be very sensitive to-changes in both-the head-bias current and the head-disk spacing. ' Fig. 1 Flux from a single transition through the thin film head.

We investigated the feasibility of a spin-dependent tunneling ͑SDT͒ read head with a parallel hard bias. In this scheme, the longitudinal biasing to the free layer is provided by fringe fields from a hard magnet which is fabricated over or under the free layer. A linear response to the applied field is achieved for a SDT junction biased with 400 Å CoCrPt underneath. Thinner CoCrPt layers yield Barkhausen jumps in the free layer. Micromagnetic simulation indicates the bias field at the edge of the free layer is smaller than that which would result from an abutted magnet. The simulation results are similar to experimental data, and indicate that shielded devices with 400 Å permanent magnet will provide stable transfer curves.