Nobuyuki Kaminaka

Magnetic head and method of making the same

A thin film type magnetic head, in which a conductor is accommodated within a groove formed in part of a ferromagnetic substrate constituting part of a magnetic core, and a ferromagnetic film is disposed on the conductor to constitute part of the magnetic core. With this structure, it is possible to reduce the number of steps of layers constituting the magnetic head for reducing damage or breakage of the stepped portions of the layers and also increase the core gap in a central part of the core so as to reduce leakage flux even in the thin film magnetic head as well as bettering dissipation of Joule heat produced in the conductor.

Magnetic head and method of production thereof

A magnetic head and a production method therefore in which permanent magnet films for applying a DC bias magnetic field Hd h to a magnetoresistive effect element film (MR element film) is arranged on both sides of the thickness dimension of the MR element film through at least a non-magnetic film therebetween. In making the MR element film thicker in order to reduce distortion, the DC bias magnetic field Hd b to be applied to the MR element film is also required to be increased. Unlike the prior art in which the above-mentioned requirement is met by increasing the thickness of the permanent magnet film under the thickness of the MR element film resulting in the problem of breakage of a film member above or under the thickness of the permanent magnet film, the invention further comprises a second permanent magnet film above the thickness of the MR element film without increasing the thickness of the first permanent magnet film. In the case of a magnetic head with a shield members of soft magnetic material holding the MR element film from both sides of the thickness thereof, the MR element film is made thicker to make reproduction possible without any distortion or without substantially increasing the gap. For this purpose, the MR element film is held on the sides above and under the thickness thereof by first and second permanent magnet films which in turn are held by the shield members. To minimize distribution of the MR element film, a comparatively high-temperature process after forming of the MR element film i.e., forming of the second permanent magnet film is effected at optimum temperature, and a magnetic field is applied along the magnetic easy axis of the MR element film.

Magnetic Properties of Narrow Stripe Co-Ta-Zr Amorphous Films

The magnetic properties of narrow stripe Co-Ta-Zr amorphous films, with induced anisotropy across the stripe width, have been investigated. The permeability of the films decreases with decreasing stripe width. This can largely be explained by the increased demagnetization field which may reduce the initial anisotropy and rotate the easy axis to a direction perpendicular to the initial easy axis, or may change the magnetic domain structure. Stress in the film may act to enhance or retard this effect, depending on the films magnetostriction constant. It is therefore important to determine an appropriate magnitude for the induced anisotropy and to choose a proper combination of the magnetostriction constant and the substrate thermal expansion coefficient. Utilizing such knowledge, thin film heads with a 5 ¿m track width have been fabricated. A reproduced voltage of 380 ¿VPP/mm-turn-m/s has been obtained in combination with Co-Cr perpendicular recording medium.

Thermal stability of softmagnetism and magnetic properties of Co-TM-Zr (TM = Nb, Ta)

Abstract Thermal stability of softmagnetism of practical amorphous Co-Nb-Zr and Co-Ta-Zr films were investigated by kinetics of the relaxation of magnetism. The origin of the superiority of Co-Ta-Zr was discussed. Spin wave stiffness constants of these materials were determined by magnetization and FMR measurement.

Analysis of Tape Floating Behaviour in VCR using Averaged Thickness Method.

The floating phenomena of the tape on the rotating drum in VCRs were treated as an air-bearing problem using the averaged thickness theory coupled with a tape deformation problem of an anisotropic thin shell equation in FEM (Finite Element Method). We obtained the floating height distribution dependence on the groove structure of the drum by computational simulation. We compared the averaged thickness model and the exact node model. We showed that the square grooves are more effective than the triangular grooves. Good agreement between the calculated and the measured results on the tape floating behaviour has been obtained. We showed the effectiveness of the structure/fluid coupled analysis using the averaged thickness theory. The computational simulation is very useful for designing the new VCR systems and determining the effects of design parameters.

Magnetic recording characteristics of a flexible disk with a non-magnetic underlayer

Abstract We have examined a flexible disk for high recording density (35 kFCI, 542 tpi), and with a maximum transfer rate of 4.5 MBPS. By setting the magnetic layer thickness at less than 0.4 μm, the media coercivity at more than 120 kA/m, and applying it to a non-magnetic underlayer, we have realized useful flexible disk media wear resistance of 2×10 7 passes.

High Density Perpendicular Magnetic Recording by Ring Head and Vacuum-Deposited Co-Cr Single-Layer Media

Investigations using narrow gap ferrite video heads and vacuum-deposited Co-Cr single-layer media are reported. The characteristics of ring head and single-layer film combinations, in particular the perpendicular recording capability, were discussed from the point of view of the di-pulse ratio (DPR) of isolated transitions. It was found that although ring head perpendicular recording capability declines as the gap length is reduced, and the isolated pulses DPR itself gets smaller, reduction in recording demagnetization due to reduction in gap length actually improved the recording density.