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The continuous reduction of head-disk spacing has made the use of supersmooth media a necessity in gaining ultrahigh magnetic recording areal density. It is shown that the padded slider technology offers a viable alternative to the ramp load technology as a head-disk interface solution for the ultrahigh areal density.

Experiments have been conducted to assess the theoretical predictions of a stiction model for a head-disc interface recently proposed [1]. One of the key predictions of this model is that the relationship between stiction and the real area of contact is non-monotonic, and that minimum stiction should occur at an optimal value of the real area of contact. The regular textures of different asperity densities, generated by the laser texturing technique, were used in this study. The single-crater type of laser bumps could be accurately simulated by either spherical bumps with an effective radius of curvature, or cylindrical bumps with an effective Young's modulus. The stiction measurement results were found to be in excellent agreement with the theoretical prediction. The comparison between the model predictions and the experimental results were made for the stiction vs. asperity height relationships for different size laser bumps, at different spacings, and at different lubrication levels. In all cases, good agreements between the model and the experimental data have been confirmed. In this study, it has also been found that a 'bonded' Zdol lubricant film still behaves like a liquid in terms of its ability to form menisci around contacting points.

The design of laser zone texture on NiP/Aluminum substrates to create below-25 nm-glide-height media is described in this paper. A range of laser parameters such as beam size, pulse energy, and temporal pulse width of a pulsed Nd-YV[O.sub.4] laser are explored to reveal their relationship to the resulting bump topography. Depending on where the head contact is formed, four major categories of bump shapes are found to exist. The single-crater bump shape was selected to conduct the low glide texture design. Stiction and glide performance are shown to be in agreement with theoretical predictions, which constitute our major design guidelines. It is clearly demonstrated that with proper texture design below-25 nm-glide-height media with low stiction and minimal wear are readily achievable even in the landing zone with laser texture.

Glass-ceramic substrates based on the lithium silicate system have been found to have excellent tribological performance, associated with the inherent bump topography produced by differential polishing of [Alpha]-quartz and a lithium silicate/glass matrix. This paper explores the extendibility of lithium silicate alternative substrates to meet the needs of recording media for use at densities approaching and exceeding 1 Gb/[in.sup.2]. Flatness, topography, magnetic performance, and resistance to environmental attack are shown to be extendible to higher density, and alternatives to the inherent bump topography are presented.

a-C:H films prepared by DC-magnetron sputtering in an [H.sub.2]:Ar mixture exhibit strong photoluminescence (PL) peaks superimposed upon the Raman scattering spectrum. PL becomes observable at a hydrogen content of ca. 34%, and increases exponentially thereafter, driven by the progressive saturation of carbon dangling bonds. In this %H range, hardness and elastic modulus decrease and CSS durability reaches an optimum. The Raman G peak position is very sensitive to deposition temperature (shift of 0.1 [cm.sup.-1]/0C) and was found to correlate with the [sp.sup.3]/[sp.sup.2] bonding ratio as measured by EELS, and therefore can also be used as a predictor of carbon tribological performance.

A novel approach to sputter texturing media disc substrates is demonstrated. A phenomenon called hillock formation is adopted in this work to make discs for high-density magnetic recording. Hillocks, small solid metal mounds projecting out of the film plane, form when compression stresses in a selected material are relaxed during temperature cycling in a sputter-deposition process. The hillock size, shape, height and areal density can be controlled by substrate temperature, texturing-layer deposition rate and thickness, and sputter gas type and pressure. Excellent contact-start-stop tribological performance exceeding 30k cycles and glide height as low as 0.75 [micro]inch are demonstrated. The technique and process are accomplished in-situ, prior to underlayer and magnetic layer deposition, significantly simplifying the disc manufacturing process. The implementation of the sputter-texture technique has the potential for lowering head flying height, minimizing disc handling, reducing defects and contamination, and effectively cutting the cost of making discs.

Switching behaviour and intergranular interactions have been studied in CoCrTa/CoCrTaPt double layer thin films sputtered on polished and textured substrates. From the combination of a low noise and a high coercivity alloy, a high quality thin film has been obtained with very good properties for high density magnetic recording media. Coercivities higher than 2 kOe, uniform switching and a reduction in the intergranular exchange coupling have been observed from the hysteresis loops, remanence curves and [Delta]M(H) technique. Also, it is shown that circumferential texturing of the substrate results in preferential magnetic properties along the texture lines such that there is an apparent reduction in interactions perpendicular to the texture direction.

This paper reports the use of CoCrTa/CoCrPtTa double-layer magnetic films to produce low-noise, high-coercivity recording media. At an optimum thickness ratio, the double layer films can reach higher coercivity ([H.sub.c]) than either of the single-layer films of the above alloys. The signal-to-media-noise ratio of the composite can be a few dB higher than that of the single-layer CoCrPtTa film. Microstructure studies revealed that the bottom-layer film not only seeds the microstructure for the upper-layer film, but also determines the noise characteristics of the double-layer film. It is suggested that the strain and exchange coupling at the interface of the double-layer films are responsible for the enhancement of [H.sub.c].

Signal-to-media-noise-ratio (SNR) and off-track-capability (OTC) were studied as a function of alloy composition and underlayer structure for alternative substrate recording media having coercivity of 2200 Oe and remanence of 1.0 memu/[cm.sup.2]. Higher Cr content up to 15 at% and Ta content up to 6% gave better SNR and OTC performance in CoCrPtTa alloys. Replacement of Cr with CrV as buffer/underlayer significantly improved SNR and OTC. The mechanism is the effective reduction of grain size and narrowing of grain size distribution while keeping the grain crystallographic structure and orientation unchanged from that using Cr underlayer. High performance discs on glass-ceramic substrates with enhanced SNR and OTC were made by optimizing buffer/underlayer and CoCrPtTa alloy composition.

The continuous reduction of head–disk spacing has made the use of supersmooth media a necessity in gaining ultrahigh magnetic recording areal density. To overcome the stiction barrier associated with supersmooth disks without compromising the head flyability requirement, texture features can be transferred from the disk surface to the slider surface, creating a new type of head–disk interface, the padded slider interface. The tribology of a padded slider interface is in many ways different from that of the traditional head–disk interface with texture on the disk only. In this article, various unique tribological aspects of the padded slider interface are discussed in detail. Both theoretical modeling results and experimental data are presented to elucidate the stiction, friction, and wear behaviors of this novel head–disk interface. It is shown that the padded slider technology offers a viable alternative to the ramp load technology as a head–disk interface solution for the ultrahigh areal density. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Magnetic media deposited on glass substrates with metal seedlayer, Cr underlayer and CoCrPtTa alloy were studied. Within each group of samples, although the bulk magnetic properties were made to be similar, the media noise differed significantly; microstructural study indicated that the grain sizes of the magnetic layers were similar. X-ray diffraction study indicated that the magnetic layer was mostly {10.0} textured, with some [00.2] and [10.1] oriented grains also present. A correlation was observed between stronger CoCrPtTa {00.2} diffraction peak and lower media noise; the Cr {200} peak in the lower noise media was also much weaker. The different crystallographic texture is likely promoted by the surface condition of the seedlayer; larger number of [00.2] grains within the mostly {10.0} textured magnetic layer may suppress the formation of large coherently-magnetized regions in the zig-zag transitions, which would result in lower media noise.

In the columnar microstructure of electroplated Co-Ni-P thin-film media there exist groups of columns with identical crystallographic orientation. Such groups are termed clusters. The size of such clusters, which can be controlled by appropriate processing, is shown to affect the media noise, larger clusters producing higher noise. We describe the evolution of the microstructure in low-noise and high-noise media.

A novel technique for incorporating rapid thermal annealing into media sputter fabrication has facilitated the production of flyable media samples. Discs are fabricated with standard processing techniques to control physical grain size and crystallite texture. A CrMn caplayer ranging in thickness between 0.5 and 5 nm is subsequently deposited to provide the Mn-diffusant necessary to achieve post-treatment exchange decoupling. While still in-situ and before application of protective overcoats, the discs are exposed to temperatures between 200 [degrees] C and 350 [degrees] C compatible with most media production processes. A threefold increase in coercive force (peak reaching ~3800 Oe) and 10 dB improvement in medium signal-to-noise ratio is observed for the optimized process. Index Terms--Boron magnetic alloys, intergranular exchange coupling, post-deposition annealing, SMNR.

Ion beam deposited carbon has been investigated for its use as an overcoat for magnetic thin film media. By using a gridless end-Hall ion source, carbon has been deposited that possesses hardnesses to 18 GPa, stress to 4.5 GPa, and densities up to 2.6 g/cc. Contact-start-stop testing of ion beam deposited carbon to fifty thousand cycles shows marked improvement in failure rate compared to hydrogenated and nitrogenated carbon. Energetic deposition of carbon thin films can lead to implantation of energetic species into the magnetic layer. Simulations have been performed to assess the vulnerability of the magnetic layer to energetic implantation of carbon. In addition, the effect of the partial pressure on the magnetic performance is assessed and a critical impurity concentration defined. Index Terms--Carbon, implantation, ion beam, magnetic poisoning..

We have simultaneously demonstrated high areal density and high data rate, in an experiment that closely mimics the operation of disc drive products. The system involves thin-film media, GMR merged heads, broad bandwidth electronics, and an EPR4 channel with post-processing. The results presented reflect a statistical sample of components, rather than one-of-a-kind devices. In order to determine the areal density accomplished, we demanded that the bit error rate performance be insensitive to significant deviations of the head position from the recorded track center. We present a thorough description of the components and the SNR budget. The areal density accomplished varies between 15.1 Gb/[in.sup.2] at 193 Mb/s, and 17.1 Gb/[in.sup.2] at 214 Mb/s. A series of areal density capability assessments was obtained by applying various margin conditions. This was done to demonstrate robust experimental results. The outcome of this work may be applied to product development. Index Terms--Recording heads, recording media, recording systems.

A comprehensive study (TEM, MFM, AFM, XRD, Recording Performance and Magnetometry) of media noise mechanisms and their relation to grain structure is reported for model, high noise contrast, CoCrPtTa thin films. The CoCrPtTa media were sputtered on to either CrMn or NiAl/CrMn underlayers causing a change in media noise power of 9dB. The changes in media noise are not related to the topography of the underlayer(s) or due to interaction effects, which the [Delta] M technique suggests are negligible in these model samples. A quantitative correlation is obtained between magnetic cluster size and media noise using an analytical first approximation of Zhou and Bertram's micromagnetic model. Index Terms -- noise, underlayer effect, longitudinal media

We have demonstrated 23.8 Gb/in.2 areal density using a merged read-write grant magnetoresistive head, with an oriented thin film medium tested with broadband electronics and enhanced EPR4 channels. The medium had high signal to noise ratio metrics that was robust unto temperatures as high as 75 °C. A unique aspect of the head design at such a narrow track width is the simultaneous enhancement of the transducer sensitivity while keeping product and system manufacturability in the forefront. The areal density was demonstrated at a track density of 45.8 k tracks/in., using photolithographically defined poles and linear density of 520 k bits/in. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Examines the extendibility of lithium silicate alternative substrates to meet the needs of recording media for use at densities approaching and exceeding 1 Gb/in2. Average disc runout; Glide prediction and peak height distribution; Stiction and water resistance of various bump textures.