The corrosion mechanisms of magnetic recording media in a high humidity environment were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and a metal elution test, where drops of nitric acid on the media surface were analyzed by inductively-coupled plasma mass spectrometry (ICP-MS) measurement (droplet-method). By observing SEM images, the corrosion on the media surface was found to have accelerated with longer exposure to the high humidity environment. Moreover, the cross-sectional TEM images proved that the lower NiP layer was invaded by moisture from the dented part of the magnetic layer due to its texture. In addition, the droplet-method analysis revealed that Co and Cr in the magnetic layer and Ni in the plated NiP layer were found to have eluted through the diamond-like carbon (DLC) film by drops due to nitric acid. The relation between the elution behavior of the elements and the corrosion process was clarified by adjusting the time the media surface was in contact with the nitric acid droplets. Based on these results, a model mechanism for corrosion behavior due to the moisture is proposed.

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  A micromagnetic analysis of single-pole-type (SPT) heads with side and trailing shields, which are indispensable for obtaining higher values of both track and linear densities, was carried out. First, quasi-static recording field distributions were obtained for various SPT shield structures and compared with those obtained from a static finite element method (FEM) analysis. The recording fields under the main pole were in good agreement, while some discrepancies were found below the shields and the return yoke. Next, time variations of the head field and magnetization processes were obtained for a high-frequency recording current and for various shield structures. Magnetization rotation in the main pole tip, which is the origin of the dynamic recording field, was strongly affected by the magnetization in the side and trailing shields.

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  A metal-compatible IC tag that operates on metal objects is presented. It consists of an antenna coil with a thin magnetic sheet core and a bottom conductive sheet to isolate the antenna coil from the electromagnetic influence of the metal object to which the tag is attached. The direction of communication to/from a reader/writer is in the plane of the sheet core and parallel to the axis of the solenoidal antenna coil. Magnetic sheet core materials were developed and tested for 125-kHz and 13.56-MHz IC tags. The experimental results revealed that the operating range remained unchanged for the 13.56-MHz IC tag and that it was reduced by 15% for the 125-kHz tag when the tags were directly placed on a 3-mm-thick iron plate.

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  Giant magnetostrictive material (GMM) is fabricated by electromechanical transformation with large magnetostriction and an electro-mechanical coupling factor. Therefore, GMM can be use to make a giant magnetostrictive actuator. However, because the thermal expansion (linear expansion) coefficient of GMM is 12 ppm/°C, expansion and contraction due to temperature change influences the stroke. This paper describes the consideration of thermal expansion compensation for the GMA, and presents: (1) the features of GMM and the principles of operation of GMA, (2) the results of thermal expansion measurements of GMA, and (3) thermal expansion compensation for the tandem structure.

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