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The current-induced magnetization switching was studied in the MTJ devices with composite free layer (CoFeB/CoFeB-oxide/CoFeB). The stable intermediate state was observed due to the multi-domain structure induced by the dipole field and large device size. Two different stable intermediate states were observed in different applied current direction. The switching mechanisms of those two intermediate states are different, which is also indicated by the switching current distribution. Reversible intermediate state was also observed at low applied current, which may be due to the domain nucleation. Index Terms--Composite free layer, current-induced magnetization switching, intermediate state, magnetic random-access memory (MRAM), magnetic tunnel junction, spin transfer.

A real density growth has enabled hard disk drives to continually fulfill the demands from new enterprise, desktop, and consumer applications. The demonstration of 100 Gb/[in.sup.2] is another milestone that was achieved recently and is described in this paper. The recording demonstration employed fully integrated magnetic recording heads and thermally stable multilayer antiferromagnetically coupled (AFC) media through a commercially available channel chip. At a track density of 149 ktpi and linear density of 680 kbpi, the achieved off-track capability with 5% track squeeze was 10% of the track pitch, while maintaining a raw bit-error rate (BER) of [10.sup.-4] or better. This yielded an areal density of 101 Gb/[in.sup.2] with measured on-track raw BER of 5 x [10.sup.-5]. Index Terms--Disk drives, magnetic heads, magnetic recording, system analysis and design.

This paper reports on a systematic study of the effect of magnetic film thickness on the recording performance of perpendicular double-layered media. We found that the signal-to-noise ratio of the media decreases with increasing film thickness. This is mainly caused by the poorer head field gradient that results from the increased gap between the pole surface of the head and the top of the soft underlayer of the media. A theoretical study confirms the experimental findings. Index Terms--Magnetic recording, perpendicular recording media, signal-to-noise ratio.

A magnetic height-height correlation function was used to quantitatively analyze the magnetic force microscope (MFM) images of the DC-demagnetized state of two thin film media. This function provided important information about the micromagnetic features of these media, including the global magnetic roughness, the local magnetic roughness, the strength of long-range magnetostatic interaction, and the degree of local intergranular exchange coupling. These features are accountable for the noise performance of these media detected by the recording head. Index Terms - Correlation function, DC-demagnetized state, media noise, magnetic force microscopy (MFM).

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.

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

Films with Cr sub-seed layer/NiAl/Cr-alloy/Co-alloy structure were sputter-deposited on surface-oxidized NiP layers on glass substrates. The effects of Cr sub-seed layer thickness on crystallographic orientation, grain size distribution, magnetic properties and recording performance were investigated. The recording performance of uni-crystal and bi-crystal media is compared and its correlation with grain size is discussed. Index Terms--Bi-crystal media, Grain size, Sub-seed layer, Uni-crystal media.

Presents a study which demonstrated magnetic data recording over 100 gigabyte per inch square. Use of a thermally stable multilayer antiferronmagnetically coupled media; Information on the dully integrated magnetic recording heads; System integration.

Presents a study that examined soft magnetic underlayer (SUL) materials for perpendicular magnetic recording application. Evaluation of the annealing effects of SUL materials; Analysis of the modeling effects of the soft underlayer on the write field; Effect of substrate on SUL.