Composite Ba-ferrite particles containing α-Fe were made by reducing Co-Ti-Sn substituted Ba-ferrite platelet particles in hydrogen gas. The crystal structure of Ba-ferrite is represented as the stacking of S and R layer, and the α-Fe in the composite Ba-ferrite particles was considered to be introduced primarily in the S layer in the Ba-ferrite hexagonal structure. The (110) plane of the α-Fe was parallel to the c plane of the hexagonal structure. The magnetic easy direction of the particles inclined to the plane for the samples with saturation magnetization larger than 62emu/g. The remanent coercivity of the particles was increased by introducing the α-Fe in the particles. These results indicated that the prepared particles were the composite magnetic particles consisting of hard material (Ba-ferrite) and soft one (α-Fe) behaving like a exchange spring magnet.

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  We have developed a spin rotator for obtaining magnetic domain images of three independent magnetization components with spin-polarized scanning electron microscopy (spin SEM). In spin SEM, the spin rotator is placed between a sample and a spin detector, and can rotate a polarization vector of secondary electrons by 90 degrees. Since the spin detector itself can detect only two independent polarization components, the rotation of polarization makes third-component detection possible. The rotator is a known crossed electric and magnetic field type. However, new hyperbolic-shaped magnet-pole-pieces and a pair of flat main electrodes with four pairs of additional electrodes make the rotator able to accommodate secondary electrons emitted from a wide area of the sample. The spin rotator has been successfully applied in detecting of the magnetization vector distribution of a recorded TbFeCo magneto-optical disk.

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  The inter-relationships among microstructure, domain structure and film magnetism have been investigated for Co-Cr films with the Cr content range between 0-32 at%, using SEM, TEM, Lorentz TEM (LTEM), including acid selective etched replica TEM. It is found that: 1. Both particulate and continuous models exist, but films with good perpendicular magnetization have particulate microstructure. 2. The film perpendicular magnetization process is a gradual Cr segregation process to form various patterns of isolated single domain Co clusters as Cr increases in an optimum Cr region (∼17-24 Cr at%). 3. The single domains are larger than columns which consisted of crystallite bundles. 4. These crystallites will be the smallest units and might give a potential bit length limit of an order of 10-10 ² nm, if recording is possible.

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  Highly c-axis oriented, single crystal films of Co_1-xCr_x (0≤x‹0.3) have been grown epitaxially on mica substrates by e-beam evaporation. The orientation relationship is basically (00.1)_mica || (00.1)_underlayer || (00.1)_Co, and [11.0]_mica || [10.0]_underlayer || [10.0]_Co. Films grown on Ru underlayers have an average grain size of 50-80nm, negligibe fcc content and very narrow c-axis dispersions (Δθ∼0.7-1.5°). For Co films (x=0), the as-grown magnetization structure are mainly 180° domain walls with a uniform distribution of cross-ties for thinner samples (≤300 Å), whilst thicker (› 400Å) ones show stripe domains. These images were analysed in detail to measure the wall widths and associated energy densities for as-grown, remanent and ac-magnetised samples. As expected, the magnetic properties of these films are composition dependent. However, for any Cr concentration, these films exhibit the largest saturation magnetisation when compared with either sputtered or evaporated samples. This enhancement can be attributed to a nanometer-scale segregation of Cr, which in these samples, could be particularly aided by the diffusion on the close-packed planes of the films with very narrow c-axis dispersions. Preliminary x-ray microanalysis and NMR data support this interpretation.

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  A Co-Cr film was prepared on polyethylene naphthalate (PEN) film using the Facing Targets Sputtering System. The microstructure of the Co-Cr film was observed using transmission electron microscopy (TEM). Although grain sizes of Co-Cr crystals were 10 nm in an initial stage of deposition, the grain sizes of the Co-Cr crystals grew to 30 nm in both middle layer and surface layer of Co-Cr films. A high resolution TEM image of the Co-Cr film showed that neither void nor amorphous region exists at the grain boundaries of the Co-Cr film. The segregated microstructure was also observed using the acid etching method. A TEM image of segregated structure showed that the magnetic and non-magnetic regions were clearly separated from each other in the crystal.

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  Co-Cr films. together with Co, Cr and some other related alloy films, were investigated by X-ray absorption fine structures (XAFS) at K-edges of Co and Cr for better understanding of the local structures. Co-Cr films showed similar extended XAFS (EXAFS) at K-edge of Co as those of Co films but showed some differences in near edges structures (XANES). Among Co-Cr films showing or not showing chrysanthemum patterns, there have been found little differences, if any, in EXAFS and XANES at K-edges of Co so far.

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  Compositional separation (CS) in Co-Cr based alloy thin films, which produces fine Co-enriched regions within grains, is expected to provide a particulate type magnetic microstructure suitable for high density magnetic recording. Towards the goal of establishing a synthetic phase diagram for Co-Cr thin films we examined the change in composition of the Co-enriched component as a function of mean Cr content. Our results show that CS occurs in single phase hcp solid solution thin films for Cr contents ranging from 5 to 22 at% Cr. The miscibility gap for Cr in the Co-enriched phase seems to be around 2 at% Cr. CS was also observed to occur in fcc Co-Mn alloy films. These results suggest that the origin of CS may lie in magnetically induced phase separation.

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  This paper focuses on some of the newer servo technologies that have been added to the actuator servo control system in order to meet the higher track density requirements for future HDD. After a brief description of the basic digital actuator servo control system, the paper focuses on the use of elliptic filters to reduce the effects of mechanical resonance disturbances. Then a short discussion follows on the position sensor errors. A development of the governing equation for the total position error consisting of repeatable and non-repeatable error components is made. Feedforward control can be used to increase track density by reducing the repeatable position error. A brief discussion is given on the use of accelerometers to protect the HDD from unrecoverable data errors caused by external shocks and vibrations. A predictive write/read inhibit decision using fuzzy logic shows a way to relax the tracking requirements. Increasing the HDD track density to 25,000 tracks/inch requires a five fold increase in todays servo bandwidth. This can be accomplished by placing a rotary micromechanical actuator piggyback on the slider. Some thoughts around the use of piggyback actuators in HDDs are given.

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  To minimize the restriction of conventional servo method, a new method used graphics for head positioning have been investigated. This paper will describe the principals of graphical construction and encoding, servo demodulation, and performance evaluation of graphics, etc. Finally for verifying this method, a 4000 TPI track density trial device is introduced.

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  Acompensation method of write off track using piggy-backed 2gap head on hard disk drive isdiscussed. The read and write gap offset of piggy-backed 2gap head is fomulated, and the measurement method for 2 gap HDA is introduced. The residual tracking error after offset-compensation is analyzed. Finally, a linear interpolation compensation is proposed, and the theoretical residual error is estimated as less than 0.1 μm.

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  A track density simulation model for a discrete track medium and an MR/Inductive head was developed based on an iterative geometric signal-to-noise ratio calculation. Using this model, we optimized design parameters of discrete track media related to track density. Our model suggests that discrete track media can achieve higher track density than conventional continuous track media.

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  In this paper a newly developed magnetic encoder system is presented that can detect absolute and incremental angular positions. The encoding is performed by combining a perpendicularly oriented code disk and a magnetoresistive read array that is placed at a distance of 50μm above the medium. Results of numerical calculations show the influence of track width and sensor height on the signal. A carrier-to-noise-ratio of 35 dB was achieved with a 400μm wide absolute code track and an appropriate barber-pole-type read sensor.

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  Customer requirements have guided the evolution and implementation of software and hardware computer data storage technologies. The concept of RAID originated with a group of researchers at the University of California at Berkeley (UCB). They were investigating the use of an array of small capacity, inexpensive personal computer direct access storage devices (DASD) managed by a special type of a controller, as an alternative to the single large expensive disk (SLED) subsystems more common on mainframe computers. The disk arrays can be configured differently to provide different levels of operational capabilities, each providing special advantages in reliability and data availability, speed and economy. Different configurations are referred to as different levels of RAID. Berkeley originally defined a basic set of RAID levels ranging from RAID, level 0 (RAID 0) through RAID, level 5 (RAID 5). The RAID technology vendors have since extended the RAID level domain by defining RAID 6 and beyond to accommodate additional functionality. Each RAID type has shown itself to be suitable for certain applications. The projected reduction in storage costs and facilities, $/GB and ft²/GB respectively, using the present RAID technology and its projected evolution are phenomenal.

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  Magnetic recording has been the dominant technology for information storage since the invention of the computer. The areal density has grown at a compound growth rate of approximately 30 % per year for the last 40 years. However, since the introduction of the magnetoresistive thin film head by IBM in 1991, the growth rate has increased to about 60 % per year. A key factor in this success has been the development of a high coercivity-low noise magnetic medium composed of a Co alloy such as CoCrTa, CoPtCr and CoNiPt. To achieve areal densities greater than 1 Gb/in², media development has diverged with emphasis on the development of quaternary alloys of Co and on research into new thin film media materials such as CoSm and Barium Ferrite. This paper will review these topics and highlight recent work on sputtered longitudinal Barium Ferrite thin films.

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  Magnetic recording disks with bicrystalline microstructures were fabricated on (100) GaAs single crystalline wafers. The coercivity of the bicrystal disk with Cr underlayer and CoCr(12%)Ta(2%) magnetic layer can reach up to 2600 Oe along the effective easy axis and 2400 Oe along the effective hard axis, accompanied with near unity coercive and remanent squarenesses. Deposition conditions, microstructures and hysteresis properties were systematically studied. The epitaxial orientation relationships are found to be {001}‹110› Cr // {001}‹110› GaAs and {11.0}‹00.1› CoCrTa // {001}‹110› Cr with -1.5% lattice misfit. The medium noise power of the bicrystal disk is measured and found to be extremely low, and remains virtually unchanged as recording density increases up to 100 KFCI. The recording properties of the bicrystal media were compared with those of the conventional media and state-of-the-art low M_rt media with similar coercivities.

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  Pb added Ba-ferrite films were prepared at the substrate temperature of 550 °C by dc magnetron sputtering and their crystallographic characteristics and magnetic properties were investigated. The addition of Pb facilitates the crystallization and improves the crystallinity for hexagonal M phase. The films prepared in this study exhibit a good c-axis orientation and the c-axis dispersion angle Δθ₅₀ is as small as 1°. The coercivities H_c⊥ and H_c // and Ms of the films are 1.0 kOe, 0.2 kOe and 240 emu/cc, respectively.

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  A new electroless-deposition bath for the preparation of CoNiP perpendicular magnetic recording media was developed and the magnetic and structural properties of the deposited films were characterized. The bath contains only four chemicals with diluted compositions, and can be operated at room temperature. In spite of such a simple condition, the films deposited from this bath show superior characteristics than those of conventional CoNiP perpendicular media; the high perpendicular coercivity up to 2500 Oe and c-axis perpendicularly oriented hcp structure with clear orientation. The in situ scanning tunneling microscopy observation of the film was performed, confirming the applicability of this bath to various in situ analyses for studying its electroless-deposition process. Such a simple deposition condition also has merit for easy fabrication of the media, thus being quite beneficial from both scientific and industrial viewpoints.

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  The effect of Ta content on the compositional distribution in Co-Cr-Ta thin films was investigated using spin-echo nuclear magnetic resonance and preferential chemical etching. X-ray diffraction studies indicated that the Ta distributed uniformly in the films. Chemical etching revealed that Ta addition controls the distribution of Co and Cr in films deposited at elevated substrate temperature, producing a finer compositional microstructure than the Chrysanthemum-like Pattern observed in etched Co-Cr films. NMR revealed that increased Ta content suppresses compositional separation. The dependence of the compositional distribution on Ta content can explain why the addition of only a small amount of Ta in a Co-Cr film is optimum for maintaining signal level while realising better noise performance.

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  In the previous work¹, we have reported Ta addition is effective in increasing perpendicular coercivity of the films with Cr content lower than 17 at% Cr region and not effective in those with higher than 19 at% Cr region. Also the higher coercivity of the CoCrTa films is interpreted as the enhanced Cr segregation than Ta segregation itself. In the present work, we studied the redistributing behaviour of solutes of the as-deposited films by analysing changes of structures and magnetic properties before and after vacuum annealing. It was found that the redistributing atomic species during the annealing is Cr rather than Ta, which is in good agreement with our previous claims that Ta enhances Cr segregation in CoCrTa system.

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  High SNR CoCrTa perpendicular recording media without reproduced output signal loss, are developed. The medium has a multi-underlayer of exchange coupled amorphous CoZrNb/in-plane hard magnetic layer of CoSm or CoCrTa/Cr. The multi-underlayer prevents the signal loss caused by the disk revolutions and also reduces the medium noise. The exchange coupling of the multi-underlayer has an effect of pinning the magnetic domain walls in the CoZrNb layer. Soft magnetic layer with high Bs and high permeability is obtained by annealing the Co-rich CoZrNb layer in a rotational magnetic field. The high permeability brings high reproduced signal output. The high SNR is resulted from the high signal output and the low medium noise.

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  CoCrTa media with a Cr underlayer were deposited by sputtering. The R/W characteristics were evaluated by using a MR head, and the medium noise was found to be suppressed and medium S/N was improved by increasing the Cr and Ta concentration. In the case of Co₇₈Cr₁₇Ta₅/Cr media with a higher concentration of Cr and Ta than widely used longitudinal recording media, (002) axis of hcp structure lie in the film plane in the initial layer of the medium, but this axis rises up from the film plane with increasing film thickness. This crystallographic structure led the perpendicular magnetic anisotropy near by the CoCrTa medium surface. And the intergranular exchange were suppressed by increasing the Cr and Ta concentration. The perpendicular magnetic anisotropy and/or supperssion of intergranular couping, improve the medium S/N of CoCrTa/Cr medium.

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  The effect of the residual magnetic flux density (Br) on the media noise in Co-Cr-Ta alloy thin films has been investigated. Longitudinal media with higher Br and thinner magnetic layer have superior media noise to signal ratio compared to media with lower Br (below 2,000 G) and thicker magnetic layer under the constant Br δ, where δ is the magnetic layer thickness. It was revealed that media noise is proportional to fluctuations in the magnetic transition region according to analysis of the readback waveform. Furthermore, ferrite media exhibits an excellent possibility for use as a low noise media at high recording densities.

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  CoCr₁₇Ta₅ films with Ti/TiCr₁₀ underlayers are prepared using an UHV sputtering system. These films show good magnetic and crystallographic properties for perpendicular recording media. Higher output and lower noise characteristics are obtained for recording densities over 200kFCI with a Co-Cr-Ta/Ti/Ti-Cr perpendicular disk when compared with a Co-Cr-Ta/Cr longitudinal disk prepared using the same sputtering system.

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  We investigated the magnetic and perpendicular recording properties of DC magnetron sputtered Co/Pt multilayer media using a single pole contact head. Thin Co/Pt multilayer films have attractive magnetic properties for perpendicular recording. This medium shows excellent recording performances relative to CoCrTa conventional media. The multilayer films sputtered at high Ar pressure have columnar microstructure. This structure contributes to large coercivities and low media noise. This paper shows the possibilities of ultra-high-density recording using combination of thin film metal multilayer media and inductive single pole head.

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  Morphology and surface roughness of Canasite, SiC, carbon, glass disk and cover glass substrates covered with 0 Å, 500 Å and 1000 Å of Cr film were studied using an atomic force microscope (AFM). This study resulted in precise qualitative and quantitative descriptions of the sample surfaces. It was demonstrated that the surface morphology of a hard disk substrate determined the appearance and surface roughness of a thinner Cr film (500 Å). Thicker Cr films (1000 Å) controlled surface roughness, when deposited on smooth surfaces, with a regular surface morphology (carbon, glass disk, cover glass). Very deep (or very high) surface roughness features of SiC and Canasite surfaces, with diameters exceeding average Cr grain size, were not only reproduced but even enhanced by the 1000 Å Cr film.

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  Recording properties in metal evaporate tape recording media is studied via self-constant modeling. Recording characteristics as functions of medium saturation magnetization and thickness is studied considering using a shield MR head for play back. It is found that reducing film thickness is more effective than reducing saturation magnetization in terms of obtaining readback voltage pulse with narrower PW₅₀. A recording density D₅₀ = 250KFCI can be obtained with medium saturation magnetization M_s = 115emu/cm³ and thickness δ = 50nm at coercivity H_c = 2000Oe. In the paper, changes of recorded transition region through the medium depth for different medium saturation magnetization are analyzed. Nonlinearity at small bit intervals are studied.

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  The variable variance model is a Preisach-type model which has been shown to be applicable to artificial magnetooptic perpendicular recording media. In this paper, this model is extended to Co-Cr perpendicular media. It is found that, for this media the variance in the interaction field is larger in the saturated state than in the demagnetized state. More general functional dependencies on the magnetization are discussed.

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  A model of magnetization reversal for the chain of two oblate ellipsoids was proposed. The magnetization loops, the angular dependences of coercivity Hc and the critical field H₀ were calculated with the consid?tions of the uniaxial magnetocrystalline anisotropy, as well as the magnetostatic interaction between the ellipsoids. It ? shown that for small anisotropy factor ω ( = 2K_J/M_s² ), the magnetization reversal of the chain is inclinable to fanning process, while for the large one, the reversal to parallel rotation process. When the crystalline anisotropy of ellipsoids was considered, the coercivity of the chain of two oblate ellipsoids was larger than that of Jacobs and Be? chain of two spheres by a factor of (l+6ω/π) for fanning process and of (1+2ω/π) for parallel ratation proc? When ω equals to zero and the ellipsoids become spheres, the results of the model become to that of Jacobs and Be? model of chain of the two spheres. It was found that the effect of the crystalline anisotropy on the magnetization reve of the chain is large than that of magnetostatic interaction between the particles. This model could be used to explain magnetization reversal mechanism of the oriented Ba-ferrite particulate media.

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  Macroscopic magnetization characteristics of recording media, which consist of many fine magnetic particles, can be calculated by use of magnetization characteristics of an isolated fine magnetic particle and the interactive field between particles. We have developed a new simulation method, which calculates the magnetization process of media taking into account particle shape and size and interparticle interaction, and analyzed magnetization characteristics and the interparticle interaction of metal-particle media and Barium-Ferrite-particle media by way of example.

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  For analysis of the interparticle interactions in thin film media, we have developed a new medium model in which prismatic particles whose orientation directions are chosen by the random number are arranged in a lattice shape with proper separations and the magnetization behavior is calculated by the curling model considering accurately the interaction field. From the simulations of M-H curves it was shown that the coercivity and the squareness were changed by the interaction and the particle clusters in which particles have the similar magnetization direction were formed in longitudinal film media even though the exchange was neglected, while such clusters were not formed in perpendicularly anisotropic media.

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  A simulation of the recording process using a VSM (vibrating sample magnetometer) and a media sample with a 6mm diameter was used to examine Co-Cr-Ta recording media. The resulting transition was compensated for by calculated true demagnetization fields. The waveform calculated with this transition was more similar to that of actual magnetic recording than the conventional simulation.

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  Numerical simulations of the recording performance of metal particle (MP) tapes as a function of improvements in the geometric (head-to-tape distance and tape thickness) and magnetic properties (saturation magnetization and coercivity) of the tapes have been performed. For the tapes considered significant improvements are possible. A total improvement relative to existing MP tapes of 6.9 dB at a wavelength of 0.5 μm is predicted.

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  Hysteresis properties and transition configurations as related to intergranular exchange coupling and out-of-plane angle of grain’s magnetic easy axis have been studied with 3D-static simulation model in longitudinal thin film media. The out-of-plane angle of easy axis contributes to release the bridgings in large exchange coupled thin film media.

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  A simplified quantitative recording model, for thick media, and for media with arbitrary easy axis orientation is reported. The model is based on an extended version of the Williams and Comstock model. Solutions of the model are determined through an iterative procedure. The model employs a minimum number of adjustable parameters. Comparisons between calculations made with the model and experimental data in the time and frequency domain indicate the model has quantitative accuracy for ME tapes.

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  To simulate the magnetic properties of magnetic domain structure in soft-magnetic films, we developed a new simulation program based on Monte-Carlo method which is a new approach for magnetic thin films. In this method any special initial state is not needed in contrast with Landau-Lifshitz-Gilbert method. We found a good agreement between the simulated results and experimental Bitter patterns. Our method is very useful for the simulation of a soft-magnetic thin film.

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  We have developed a novel numerical simulator for analysis of soft-magnetic thin films, which is based on a finite-element method modified for interparticle interaction and a particle assembly model for a magnetization in a magnetic film. The static magnetization process and the magnetoresistive effect in permalloy stripes are modeled and a good agreement between the simulation and experiments was obtained. Our approach has very high calculation speed compared to conventional numerical simulations like the Landau-Lifshitz-Gilbert method.

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  This paper presents a new theoretical analysis of the magnetic field of a single pole having a varying magnetisation through its thickness and in the presence of an underlayer. Fourier analysis is used to obtain an exact solution in the form of infinite series but a simple approximation derived from this solution is shown to give accurate results. Vertical field calculations, output spectral response functions, roll-off curves, peak shift and D₅₀ results for particular magnetisation distributions indicate improved replay performance in comparison with a conventional constant magnetisation pole.

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  Magnetic data storage possesses the potential for extremely high bit density exceeding 1 Tb/cm² or about 10 Tb/inch², which corresponds to storing each bit into each ferromagnetic fine particle composing a magnetic storage medium. We call this perpendicular spinic storage (PSS)' because this tremendous potential of extremely high bit density could only be established by perpendicularly magnetizing ferromagnetic particles, or parallel spin clusters, arranged systematically and oriented perpendicularly on a substrate. The possibility and the background of terabit PSS in magnetic storage technology are discussed from the viewpoint of theoretical considerations and the current situation in high density recording. To approach this tremendous possibility, main-pole thick width (MPTW) recording of several hundreds nanometer in width and dispersive writing and collective reading (DWCR) with a multiple-track head are proposed.

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  In recent years, efforts in the industry to reduce head/media spacing loss and increase areal recording density, for the most part, have been directed toward reducing the size and mass of air bearing sliders to enable very low flying height. An alternative to this strategy aims at operating ultra low mass heads in continuous sliding contact with the media. This paper, will summarize the progress that has been achieved at Censtor Corp. over the past several years in this latter approach to extending recording density, which is now being implemented in small form factor disk drive designs.

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  The read/write performance of a single pole type head was greatly advanced by increasing the magnetic circuit efficiency. These developments have enabled recording densities of 530 Mb/in² without MR and PRML technology. In order to achieve higher recording density, we have investigated CoZrNb films deposited by ion beam sputtering. It is confirmed that an increase of the amount of incident particles with a large incident angle leads to improve the magnetic properties of CoZrNb films in the thickness range less than 2000 Å.

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  Soft magnetic properties of CoFeB films (with 1μm thick) produced by electroless-deposition were investigated. The coercivity, Hc, of the film sharply changed due to the film composition and showed the minimum at the composition of Co₈₉Fe₉B₂at%, whereupon high Bs value of 1.6T was obtained. The optimum film consisted of fccCo fine grains 10∼15nm in diameter. Applying the external field during deposition improved the soft magnetic properties. The Hc values of easy and hard axes were lower than 1 Oe. Moreover, thicker film up to 3μm also exhibited low Hc. Effect of annealing with applying external magnetic field was also investigated, clarifying that the anisotropy field, Hk, decreases from 30 Oe to 10 Oe and the highest permeability of 1600 is achieved at annealing temperature range of 200°C∼400°C, with magnetostriction, λs, +5.37x10^-6.

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  Electrodeposited FeP alloy films were formed, and the most suitable FeP alloy film exhibits a minimum coercivity, 0.2 Oe, and high saturation magnetic flux density, 1.4 T, at the composition of 27at%P. In order to improve the magnetic properties, in particular, the permeability, the magnetic field heat treatment was adopted, and the permeability increased until 1400. The most suitable FeP film was found to be a hyper-fine crystalline structure. The thermal stability of the FeP film was also confirmed to be until 300°C annealing without magnetic field in vacuum.

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  The purpose of this study is to obtain a soft magnetic film with high saturation flux density Bs and permeability μ and controllable uniaxial anisotropy. Making a multilayer structure using Fe-N for which Bs is close to that of pure Fe and Co-Zr-Nb, a soft magnetic film having Bs∼19 kG, Hc≤0.3 Oe Hc and μi≥3300 at 1 MHz was obtained. This film retains the soft magnetic properties up to 450C, and the μi at 1 MHz annealed at 250C is greater than 4000. The uniaxial anisotropy field Hk in the range of 4 to 7 Oe can be induced by annealing while retaining the soft magnetic properties.

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  The soft magnetic properties and domain structure of Fe-N-O films were examined for the purpose of thin film head application, as a function of nitrogen and oxygen partial pressure during sputtering. The introduction of a very small amount of oxygen along with nitrogen can effectively reduce the grain size of Fe, resulting in a decrease in the coercivity. Fe-N-O films with a high saturation flux density (20 kG), low coercivity (0.6 Oe) and large permeability (4000 at 1 MHz) can be obtained by sputtering in a mixture atmosphere of nitrogen and oxygen. Even though the domain structure of the Fe-N-O film contains large triangle domains, it can be improved prominently by forming an amorphous Co-Zr underlayer. In conclusion, Fe-N-O/Co-Zr double-layered films are possible for thin film head applications.

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  Preparation conditions of ultra thin Fe-Si-N films for a single-pole type head have been investigated by using an rf sputtering with N₂ addition. High frequency (10MHz) permeabilities of 2000 - 3000 have been obtained for sheet films with a small anisotropy dispersion by controlling the N₂ quantity. High frequency permeability of strip patterned samples was also investigated. The Fe-Si-N/Si₃N₄ multi-layer stacked with ultra thin sheet films shows higher permeability than that of an Fe-Si-N single layer when the strips width is narrower than 20 μm. This may be attributed to the reduction of the demagnetization at the strip side edges.

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  In Fe-Si-N films, the nitrogen content and the double-layered construction improve the soft-magnetic properties and the domain structures. The readback output of the Fe-Si-N single-pole head increases and the head noise is induced with increasing the nitrogen content. On the other hand, the Fe-Si-N/SiO₂ double-layered head shows extreme output deterioration. These phenomena are related to the stress anisotropy.

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  We introduce a novel vertically stacked lead structure for multiple head/track systems which can reduce inductive coupling between lead pairs by several orders of magnitude. We develop an analytical expression for the coupling of both vertically stacked and conventional side-by-side lead pairs, and compute the inductive couplings. The sign as well as the magnitude of the mutual inductance between lead pairs depends on their relative displacement. This dependence provides opportunities for cancellation. Also, because of the balance between positive and negative contributions to the mutual induction, the coupling between lead pairs does not necessarily decrease monotonically with distance. The results presented here provide design information for the tradeoffs between crosstalk, spacing, and fabrication costs.

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