Akito Sakemoto

MAGNETIC PROPERTIES OF FE-CU AND FE-P ELECTRODEPOSITED ALUMITE FILMS

Cu and P were examined as additives to decrease the perpendicular coercivity of Fe-electrodeposited alumite film. Addition of Cu and P to the Fe particles decreased the coercivity to less than 1000 Oe, and P was a more effective additive than Cu in decreasing the coercivity. In the Fe-Cu system, Cu atoms are considered to be dispersed uniformly in the Fe matrix because no drastic changes in the morphological, crystallographical and magnetic properties were observed. In the Fe-P system, P is considered to be precipitated between Fe microcrystallites because the crystallographic continuity of the Fe particles was deteriorated, and distinct microstructure was observed in the Fe particles when P was added. Drastic decrease in the coercivity of Fe-electrodeposited alumite film is considered to be mainly due to the discontinuity of the Fe particles in a system containing P.

CO-P ELECTRODEPOSITED ALUMITE FILMS WITH IN-PLANE MAGNETIZATION

The magnetic properties and corrosion resistance of a magnetic alumite film, in which micropores are filled with Co, are investigated. It is found that in-plane magnetizatlon film is obtained by adding a small amount of P to the Co. For example, the effective anisotropy energy of the film changes from +0.44×105 erg/cm3 to -1.32×105 erg/cm3 by the addition of 8 at.% P. The in-plane coercivity of the film can be controlled between 340 Oe and 1350 Oe by the P content. The corrosion resistance of the film filled with Co94P6 under the atmosphere of 40°C, 90% R. H. with 10 ppm SO2 gas is tested. The corrosion resistance of the film under this condition is superior to that of sputtered Co-Ni thin film media with a carbon protective layer. Magnetic alumite film filled with Co-P alloy is considered to be a candidate for longitudinal magnetic recording media.

Recording characteristics of high density metal powder floppy disks

Abstract A combination of metal powder coated medium and metal-in-gap head provides sufficient read/write characteristics to develop 5.25 inch, 10 Mbyte floppy disk systems, in which a 40 k fci-127 tpi format is adoped. This has been achieved mainly by the optimization of medium coercivity, and of head gap length as well as surface smoothing to less than 12 nm in RA.

Rotationally symmetric wavefront coding for extended depth of focus with annular phase mask

Wavefront coding (WFC) with a cubic phase mask (CPM) for extended depth of focus (EDOF) has been studied since 1995. However, the asymmetric surface shape of a CPM has several disadvantages, such as necessity of a square aperture, directional artifacts in images, rotational adjustment during assembly, defocus-dependent lateral image displacement, and difficulty in fabrication. To overcome these disadvantages, we propose an annular phase mask (APM) with a rotationally symmetric form. An APM adds the phase of the parabolic profile in plural annuluses and phase steps between annuluses to the penetrating light. We confirmed an EDOF effect comparable to that of a CPM in our APM design by simulation. The depth of focus of a WFC system with the APM was estimated to be about 6.8 times larger than that of a conventional system. The effect observed in the experiments using a fabricated APM is consistent with the simulation result.