K. Oka

Unitika, Ōsaka, Ōsaka, Japan

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Publications (2)2.84 Total impact

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    ABSTRACT: Co-Fe-Si-B films have been prepared using a roll coater and DC magnetron sputtering system onto a polyethylene terephthalate substrate. This thin film exhibited an excellent uniaxial anisotropy introduced by an asymmetric thermal shrinkage of the substrate. Reversal with a single large Barkhausen pulse has been observed in thin film structure 1 mm by 50 mm by 0.65 μm. Closure domains have been clearly identified at the film ends. The threshold for the reversal is the coercive force. The reason for reversal with a single Barkhausen jump is that the long narrow film geometry has essentially zero demagnetizing field over most of the film. Once the walls start to move through the center portion of the film, there is nothing to stop them so the reversal proceeds with a single large Barkhausen pulse
    IEEE Transactions on Magnetics 10/1996; · 1.42 Impact Factor
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    ABSTRACT: Thin films of FeC were deposited onto a polymer substrate by reactive DC magnetron sputtering, using an argon and hydrocarbon gas mixture. The polymer web is wound by a roll coater, and an individual thin film with a constant thickness is piled up by increasing a number of passes UP to a desired thickness. Uniaxial films with Hk=4000 A/m and low dispersion were obtained. The coercive force was a function of thickness; it was Hc=8 A/m for films 0.8 μm thick. The easy axis of the uniaxial anisotropy was along the direction transverse to the rolling direction of the polymer web. The origin of the uniaxial anisotropy is the anisotropic thermal shrinkage of the polymer web is discussed by a model
    IEEE Transactions on Magnetics 12/1995; · 1.42 Impact Factor