N. Tsuya

Perpendicular magnetic media by anodic oxidation method and their recording characteristics

Magnetic alumite films containing electrodeposited Ni, Co and Fe were successfully prepared by employing an additional new process in the conventional anodic oxidation method in order to obtain suitable perpendicular coersive force below 1000 Oe. By this new process, the diameter of the micropores in the oxide layer was widened above 400 A. The recording characteristics of the 5.25 inch rigid disks were evaluated using a Mn-Zn ferrite ring head with a gap length of 0.5μm. A recording density D50 of 42 kBPI was obtained for the disk with a media thickness of 1.5μm and a coercivity of 950 Oe. The output voltage was 1.2μ Vpp / μm. turn at 20 kBPI. Higher recording density of D50 was expected for the disk with a media thickness below 1.5 μm. It was shown that the present medium exhibit higher potential for recording than a conventional plated medium at high recording density region.

Alumite disc using anordic oxidation

Perpendicular magnetic alumite discs were obtained using an anodic oxidation method.The additional new pore widening process was effective to control the coercive force. The electro-deposited fine iron needles were single crystals and the growth direction was [110]. The recording characteristics of 3.5 and 5.25 inch rigid discs were evaluated. A recording density D 50 of 50 KBPI was attained for the disc with a media thickness 1.5 µm. The environmental test under an atmosphere of of 40 °C 90 % R. H. over 1000 hr affirmed the stability of the alumite disc with 250A SiO 2 overcoat.

A perpendicular magnetic recording medium by alumite

Abstract Magnetic properties of electrodeposited alumite media for perpendicular recording were investigated. By means of the pore widening process enabled to realize the coercive force less than 1000 Oe. Mossbauer spectra suggested that the direction of magnetization of the processed alumite was almost perpendicular to the surface.

Application of a Chua type model to the loss and skin effect calculations

Previously, we have proposed a specific Chua type model, and shown that our model is closely related with the Preisach and Rayleigh models. In the present paper, a simple linearized Chua type model is proposed for the loss and skin effect calculations. As a result, it is found that the hysteresis makes the skin depth deeper.

A representation of magnetic aftereffect

A chua type magnetization model is presented and closely examined to the other models. As a result, it is revealed that a Chua type model is closely related with the Preisach type model and gives the Rayleigh relationships in the weakly magnetized region. Moreover it is shown that the magnetization processes are essentially accompanying the magnetic aftereffects.

A representation of magnetic hysteresis

Preisach and Chua type models for magnetic hysteresis are studied with respect to their principal idear for modeling. This paper elucidates that both the Preisach and Chua typemodels can be derived from a common picture. Also, this paper proposes a specific model that can embrace essential parts of both Preisach and Chua type models.

A representation of magnetic hysteresis by fourier series

Abstract The magnetization characteristics are separated into the saturation and hysteretic properties by the Fourier series while the induction is sinusoidally varying with time. These two properties yield the parameters of a Chua type model, which is closely related with the Preisach type models.

An amorphous magnetostrictive delay-time cordless digitizer

A digitizer with a cordless cursor to input the coordinates of graphics is reported. The digitizer utilizes magnetostrictive delay lines made of iron-based amorphous ribbons. During the propagation of a magnetoelastic wave ion the ribbon, the output signal is generated by a solenoid coil wound through the entire ribbon length when the wave arrives at a position immediately underneath the cursor magnet. The resolution of the digitizer is +or-0.1 mm; the cursor position was still detectable even when placed 12 mm above the pad surface. >

Faster magnetic field computation using locally orthogonal discretization

Because of their simplicity and flexibility, first order triangular finite elements are the most widely used type of finite element in magnetic field computation. However, in the first order finite element procedure, a relatively large number of mesh points is required to obtain good solutions. In order to overcome this difficulty, we propose a new method of magnetic field computation based on locally orthogonal discretizations. Memory requirements and solution times are dramatically reduced by the new method.

Microtribology of alumite disc using anodic oxidation

Magnetic alumite disks were fabricated using an anodic oxidation method. An additional chemical texture process was effective in improving tribological properties. The recording characteristics of 10-, 20-, and 30-nm-textured disks were evaluated. A recording density of 50 kb/in was attained at 5 MHz and 5 m/s relative speed. Environmental tests were carried out, with excellent results. >