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A hard/soft magnetic composite pillar array medium(CPA media) is proposed for Tera-bits/inch 2 recording. The recording frequency of 1.5 GHz is considered to be necessary to obtain high data rate with 1 Tbits/inch 2 recording rensity. A magnetization switching time for the single hard/soft magnetic composite pillar was evaluated using a micromagnetic simulator based on the Landau-Lifshitz-Gilbert equation. The switching time less than 0.33 nano second was found to be attained by appropriately setting the damping constant, the incident angle of applied field, and the exchange constant between the hard and soft magnetic units. The influence of the neighboring pillars in the array was also evaluated. The CPA media was found to be available for the high frequency recording corresponding to 1.5 GHz.

Relationship between coercivity and micromagnetic structure was estimated using a micromagnetic simulator assuming permalloy film as a magnetic film. Wire-like shaped magnetic film showed relatively high coercivity and the magnetization reversed thorough coherent rotation. Coercivity was found to relate to the micromagnetic structure, and large sized film tends to configure vortex micromagnetic structure and coercivity becomes small.

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A hard/soft magnetic composite pillar array medium is proposed for the ultra high density recording medium. Magnetization reversal process for a single hard/soft magnetic composite pillar in the medium is calculated using the Landau-Lifshitz-Gilbert equation. In the case that the pillar size which corresponds to 1 Tbits/inch 2 or higher areal recording density, magnetization vectors for the soft magnetic unit do not form a domain wall nor a vortex. Hence, noise caused by the domain wall or the vortex for the soft magnetic unit is considered to be none. Magnetization reversal of the soft magnetic unit helps the magnetization reversal for the hard magnetic unit, reducing the effective coercivity for the hard magnetic unit greatly. Accordingly saturation recording to the high-Ku hard magnetic material used for perpendicular magnetic recording will be realizable.