Magnetic recording performance of inductive heads with hybrid top-pole structures consisting of thin sputtered FeN/Ta multilayers and thick electroplated NiFe was studied. Conventional 42-turn, 4-layer thin-film inductive heads were used and emphasis was placed on writability. Heads with hybrid toppole structures displayed improved overwrite and nonlinear transition shift performance compared with NiFe-only heads.

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To achieve ever-increasing areal density, magnetic recording heads are required to operate at ever-decreasing trackwidths. The shield width of a magnetoresistive head is an important factor in the off-track performance of the head. Reducing the shield width at the ABS will reduce the off-track inductive response (inductive pickup by MR device acting as a one-turn inductive head with trackwidth equal to the shield width) at the cost of increasing the off-track magnetoresistive response. In this study, the effect of the shield width at the ABS on the off-track inductive and off-track M R noise was examined.a shield-to-shield spacing of 0.31 p, bottom and shared shield thicknesses of 2.0 pm and 3.5 pm, respectively, a smpe height of 1.8 pn, and a flying height of 63 nm. The disk had an M& of 1.0 memu/cm2, a of 2200 Oe, and a linear velocity of 620 ips. The low frequency was 7.0 MHz. The cross-track geometry studied is shown in Figure 1.Using a finite-difference model and common assumptions about the potential at the ABS [ 11, the head potential is modeled for various shield widths. A sample potential profile is shown in Figure 2 for a shield width of 20 pm. 3D reciprocity was used to calculate the response to a microtrack as a function of off-track position. This will be discussed. In the model, the shield width, w, was varied from 2.6 pm (shields flush to the MR element) to 150 pm.Focused-Ion-Beam etching was used to fabricate devices with shield widths varying from 6 pm to 150 pm. The depth of the etched region was 1 pm. To measure and visualize off-track pickup in an intuitive way, a center track was written at the low frequency (LE). 20 tracks were written toward the ID at a frequency of (LF-n*50 IcHz), where n is the number of tracks from the center track, and 20 tracks were written in the OD direction at a frequency of (LF+n*50 IcHz). The track pitch was 4.2 lun. The head was placed on the center track and the signal was analyzed by a spectrum analyzer. The magnitude of the signal at a given frequency (LF+n*50kHz) measures the amount of off-track pickup from the nth track. Figure 3 and 4 show the inductive response (bias current off) and the total response, MR plus inductive, (bias current on) for a sample shield width of 10 p Figure 5 and 6 show the inductive response and the total response, M R plus inductive, for a sample shield width of 150 pm, The head with the 10 pm shield width clearly shows less off-track inductive signal from the outlying tracks as well as a significant decrease in the noise floor in that region. An increase in the off-track MR response (total response minus inductive response) is not seen at this shield width. The left-right asymmetry in the total response is due to anisotropic flux propagation in the MR element.The response for all shield widths and the optimum shield width at the ABS, based on minimizing the two noise sources considered here, will be discussed.The head studied was an MR head with a read trackwidth of 2.6 References[I]

We have measured field emission from 0.2 pm thick, smooth polymeric-based diamond-like films deposited on silicon wafers, Figure 1. The polymer is a random-network carbon-based polymeric precursor to DLC that is tetrahedrally hybridized and bound via single bonds to three other carbon atoms and one substituent with the formula [CRIn. This polymer is made via a Wurtz-type coupling reaction that produces a soluble polymer that can be applied in the same manner as photoresist. The films were formed on boron-doped Si <111> wafers that had been chemically stripped of its native oxide. The polymer was applied using a photoresist spinner (450 rpm, 3 min), dried under vacuum, and then baked at 500 "C for 7 hours in a nitrogen atmosphere. Compared to polycrystalline diamond films of similar thickness that exhibit significant surface roughness, these polymeric-based films are very smooth after curing.The Raman spectra of these amorphous films show typical sp2 (at about 1600 cm-') graphitic bonds and a fair amount of sp' (at about 1350 cm-') bonds indicating the presence of diamond, Figure 2.Prior to field emitter testing, the samples were checked for vertical conduction by placing a tungsten probe on top of the films and measuring the I-V curves up to 100 V using an Agilent Parameter Analyzer. The I-V curves exhibit some non-linearity and yield currents ranging from 30-60 pA at 100 V. This results in saturation effects in the emission curves, at elevated extraction voltages, due to the series resistance effect of the films. For many applications this is a desirable feature since it prevents catastrophic burnout of the emission sites at high current densities.Emission testing was performed in a custom-built, ion pumped vacuum test station at the University of Illinois at Chicago at pressures of about 1~1 0~~Torr. Electrons were extracted from the diamond films by placing a 3 mm diameter, flat polished, tungsten probe at distances of 50, 75, and 100 pm above the film surface. Measurements were also performed at room temperature, 75, 100, and 125 "C using a built-in heater system. Results follow typical Fowler-Nordheim behavior with its characteristically strong shift of the I-V curves to higher voltages with increasing emitter-to-extraction electrode distances. Also, very weak temperature dependence was observed. Except for one sample, very little adsorbant-enhanced emission was observed. This type of behavior can usually be observed in carbon-containing emitters such as carbon nanotubes [ 11. Extraction fields ranging from 10-15 V/pm were observed which is respectable for these non field-enhanced films (no surface protrusions) and macroscopic current densities of 3 mA/cm2 were measured. (This also compares well with CNT results [l]). The macroscopic current density is defined by the maximum emission current (0.2 mA) divided by the area of the extraction probe. Figure 3 shows a typical I-E curve measured at 75 ' C and a cathode-to-anode distance of 75 pm and Figure 4 shows the corresponding F-N plot.heinz husta@cahotcmu.com,...

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