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The mechanical, physical and tribological characteristics of ZrO2-Y2O3-Ta2O5 were investigated. The results showed that the frictional coefficient of the material was less than half of the Al2O3-TiC sample. Under contact conditions, damage was measured at 0.2 dB and slicing resistance changed from 1 to 3 mol % Ta2O5. The incorporation of Ta2O5 had a stabilizing effect on the tetragonal phase.

The magnetic field distributions of overwritten patterns on rigid thin film disks were investigated using magnetic force scanning tunneling microscopy. The results showed that at high densities and offsets smaller than 2 micrometers, track width modulation was induced along the edges by overwritten transitions. These effects were less conspicuous at low densities.

Wear at the head-disk interface of magnetic recording devices depends on the take-off velocity (TOV). At a lower TOV, the sliding distance between the head and disk prior to take-off is shorter, and the tribological performance is improved. Disks prepared with a cross hatch texture can produce a low ratio of center line to peak/peak to valley (R(sup p)/R (sup t)) and a low bearing ratio (t(sup p)). This type of texture leads to a low TOV. However, some cross hatch textured disks and most circumferential textured disks have a high R(sup p)/R(sup t) and t(sup p), leading to a higher TOV and poorer tribological performance. Heads with negative crowns and negative skew angles also lead to a higher TOV and poorer performance between the head and disk.

Head-disk contacts in a disk file with a rotary actuator are examined during load/unload using laser Doppler vibrometry and acoustic emission techniques. A novel scheme that allows tracking of the slider with the laser beam of a laser Doppler vibrometer during load/unload is implemented. Head-disk contacts are found to occur as a function of the velocity of the slider along the inclined ramp prior to loading, and it is shown that a low vertical loading velocity is less likely to introduce head-disk contacts than a high loading velocity.

Scanning and transmission electron microscopy studies were conducted to investigate the wear behavior of unlubricated polycrystalline zirconia overcoated disks. The results indicate that the overcoat is susceptible to cracking in the direction of sliding. The tendency for crack formation appears to be related to the presence of a residual stress in the sputtered overcoat and also to nanometer scale porosity at the grain boundaries. X-ray diffraction results suggest that the overcoat is under compressive stress.

We have demonstrated that the direct overwrite (DOW) Magneto-Optical (MO) disk to which we have added a GdFeCo Readout layer shows a 21% window margin for data recorded at 0.54 micrometer/bit density, twice the first generation recording density. The addition of a GdFeCo Readout layer raises the carrier level and lowers the modulation noise level several dB. This improved DOW-MO disk also shows a C/N of 53 dB at 0.75 micrometer mark length, which is several dB higher than is typical for the first generation MO disks. We have recorded data at a density of 0.54 micrometer/bit on the improved DOW-MO disk, using a write precompensation scheme in the timing of laser power. We have achieved a 21% window margin in discrimination of the data recorded at this density. A different write precompensation scheme which enhances falling edges of laser pulses also demonstrates a remarkable improvement in discrimination of these high density recordings on the improved DOW-MO disk. Using this improved DOW-MO disk and write precompensation schemes, we have concluded that 5.25 inches DOW-MO disk could have 1 GB/side capacity which could be the next generation ISO standard capacity.

The possibility of high density overwrite recording using the light intensity modulation method in the magneto-optical disks has been investigated. It was found that the area around a mark written by irradiation of high power was erased spontaneously regardless of the pre-recorded states. It is effective for high linear density recording. On a disk with a track pitch of 1.4 micrometer, signal deterioration by thermal interference was not observed after recording at an adjacent track with an off-track of 0.2 micrometer. It is expected that higher track density recording can be achieved by using the multi-pulse recording method.

The effect of relative humidity on friction behavior of the head/disk interface was investigated experimentally. Thickness of adsorbed water on both head and disk surfaces was measured at various relative humidities using an ellipsometer. Lubricated disks adsorbed less water than unlubricated disks, and an optimal thickness of lubricant was found for the least water adsorption. It was found that total liquid thickness (lubricant and adsorbed water) on both contacting surfaces was better correlated with static friction coefficient, compared with total liquid thickness on the disk surfaces only or total water thickness only at the head/disk interface.

The magneto-optical recording performance of Co/Pt and GdTbFe-based disks was compared at three wavelengths. At 820 and 647 nm, the carrier to noise ratio of the GdTbFe disks was higher (2-3 dB) due to a lower noise level. At 458-nm wavelength, Co/Pt performed 3 dB better than GdTbFe, which was the overall result of a higher Kerr signal in Co/Pt, the regularity of the written domains, and a low noise level, comparable to that of the GdTbFe disk. The crystalline microstructure of Co/Pt did not cause a higher noise level than that of GdTbFe.

The new 4 Megabyte flexible disks utilize unoriented coatings of Barium Ferrite particles. Comparing the disks from ten different manufacturers we observed considerable differences in soft error rates, and the object of this study was to determine the main causes for these differences. A detailed magnetic and thermomagnetic analysis revealed significant differences between the various disks, but not sufficient to explain the differences in error statistics. We conclude that the error differences originate primarily from the differences in high frequency (short wavelength) modulation caused by surface roughness variations.

The importance of the multilayered nature of the head-disk interface (HDI) on the van der Waals (vdW) interactions is illustrated by presenting the calculation of the Hamaker functions for increasingly complex layered structures. The results indicate the necessity of performing the full Lifshtiz calculation on a realistic layered model of the HDI for accurate force modeling.

A number of interfacial adhesive models are implemented for simplified head-disk interface (HDI) configurations and realistic roughness conditions applicable to actual HDI's are modeled. It is found that while the contact force is negligible for an interface with low roughness, the adhesive force dominated such interface.

Scientists at the Computer Microtribology and Contamination Laboratory (CMCL) at Ohio State University conduct research in the tribology of magnetic storage systems--namely, tape drives, flexible disk drives and rigid disk [...]

We tried to realize Gbits/[in.sup.2] class Floppy Disk with a magnetic layer prepared by sputtering (SP-FD). The heat-durable undercoat and the underlayers made magnetic layer have Gbits/[in.sup.2] properties, with higher S/N and narrower PW50 in comparison with those of 3.1 Gbits/[in.sup.2] HD. Heat durable substrate, fine protrusions and aerodynamics consideration allowed to achieve stable and nonaggressive contacts and good durability after running for more than 250 hours at three different environment conditions. We can conclude that the SP-FD has the potential of 3Gbits/[in.sup.2] FD Index Terms--Magnetic recording, head-disk interface, thin film, floppy disk.

We observed the readback signal from a floppy disk (FD) media prepared by a novel magnetic contact duplicated method. The signal amplitude, PW50, and CNR were nearly same as that using the traditional method. It was confirmed that this technique has the high potential to write servo signals in high Hc media. Index Terms--Magnetic contact duplication, servo-writing, floppy disk.

A novel magnetic contact duplication technique is proposed in order to write a servo signal on hard disks and floppy disks at a high speed and a low cost. In this technique a magnetic layer of a master disk is lithographically patterned in accordance with a servo signal, having low coercivity, and dc magnetic field is applied to a slave disk contacted with the master one. A computer simulation using finite element method shows that the pattern of the master disk can be duplicated on a slave one. The possibility of duplication by using this technique is confirmed from experimental results in which a Bitter pattern of a duplicated slave medium is clearly observed. Index Terms--Magnetic contact duplication, servo-writing, hard disk, floppy disk.

The problem of optimally placing data on disks (ODP) to maximize disk-access performance has long been recognized as important. Solutions to this problem have been reported for some widely available disk technologies, such as magnetic CAV and optical CLV disks. However, important new technologies such as multizoned magnetic disks, have been recently introduced. For such technologies no formal solution to the ODP problem has been reported. In this paper, we first identify the fundamental characteristics of disk-device technologies which influence the solution to the ODP problem. We develop a comprehensive solution to the problem that covers all currently available disk technologies. We show how our comprehensive solution can be reduced to the solutions for existing disk technologies, contributing thus a solution to the ODP problem for multizoned disks. Our analytical solution has been validated through simulations and through its reduction to the known solutions for particular disks. Finally, we study how the solution for multizoned disks is affected by the disk and data characteristics. Index Terms--Performance modeling and prediction, disk technologies, zoned disks, data placement.

An accelerated direct extraction test was developed to evaluate the cobalt migration in thin film rigid disk. The results obtained using this test show good correlation to the results from the conventional chamber exposure test at 60 [degrees] C, 70 [degrees] C, and 80 [degrees] C with 80% RH for 96 hours.

Thermal asperity (TA) sensors have been used to study head/disc interface dynamics. TA sensor voltage output fluctuates in proportion to the head to disc spacing changes directly above the sensor. Spacing fluctuations occur in response to system resonances and other excitations. By analyzing the frequency content of the TA sensor output the excitation sources have been identified. The TA sensor is found to detect disc run out, micro waviness, disc flutter, suspension modes, air bearing resonance and slider body vibrations. Collapse of the interface, i.e., the unsteady slider dynamics, following collision with a 'triggering asperity' is also investigated. Index terms--thermal asperity, TA, head/disc dynamics

High speed video camera observation of a slider behavior after an external shock revealed that the slider jumps first and then re-contacts with the disk at its leading edge. We found an imprint at the re-contact position on the disk. We developed a suspension system that has a roof in the load beam that reduces the re-contact angle and the contact stress. We found that a magnetic disk device incorporating the system sustained no read errors for the external shocks up to 700 G. Index Terms--disk damage, external shock, shockproof suspension, slider behavior

The formation of new TA, defined as the TA generated after a drive has passed all the tests of a manufacturer, is analyzed theoretically and tested experimentally. The factors affecting the new TA are identified based on force balance analysis. Experiments are carried out on two types of ABS with different leading edge designs. It is found that the leading edge geometry markedly affects the formation of new TA. Index Terms--ABS design, particle embedding, TA.

The redistribution of a thin perfluropolyether lubricant film on magnetic rigid disks after sliding was studied by mapping the surface reflectivity under polarized light using an optical surface analyzer. Both lubricated and nonlubricated regions were created on the disks with a special dip-coating process, and a drag test was conducted with the head placed in the smooth data zone. Due to sliding, a portion of the lubricant film in the initially lubricated regions was displaced into the nonlubricated regions. A numerical procedure was developed to determine lubricant thickness profiles from the surface reflectivity data calibrated by FTIR. The displaced lubricant volume increases with increasing sliding time, increasing initial lubricant thickness, or decreasing sliding speed. Local removal of a lubricant film was observed after long-term parking of the head, and surface diffusion was examined for the diminishing displaced lubricant band. Index Terms -- Diffusion, head-disk interface, lubricant, perfluoropolyether

The equivalent of Moore's law for magnetic recording is that the areal density of magnetically written bits increases at 60% to 100% per year. To achieve this, the noise in […]

The addition of storage capacity in computer disk drives by reducing the thickness of the protective disk overcoat has been a keenly investigated area in research about magnetic recording technology. A study was therefore conducted to investigate amorphous CNx overcoats with three nitrogen concentrations spanning the range from a:C to a 'good' CN film to a CN film with too much nitrogen. Results of the study are discussed.

Direct-current modulation noise is caused by the nucleation of isolated regions of reversed magnetization in thin-film magnetic media. The noise results in the development and the coalescence of the isolated regions with greater reversed magnetism. The boundaries are called pseudotransitions and produces varied magnetization and magnetic fields that are detected by the recording head.