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Magnetic properties and read-write characteristics of Co-CoO obliquely evaporated tape provided with a CoO under-layer were investigated. By forming a fine CoO crystal plane on the underlayer surface and optimizing the thickness and oxygen flow rate of the magnetic layer, we were able to make a medium with a coercivity,, Hc = 240 kA/m, the highest for the Co-CoO obliquely evaporated media. This medium also shows a decrease in the switching field distribution compared to the conventional medium. The read-write characteristics of this medium present a narrower half-amplitude puls-width (PW50) and a higher output than conventional medium. The obtained results suggest that providing an underlayer brings about a sharp magnetization reversal. [ABSTRACT FROM AUTHOR]

The growth mechanism that determines the microstructure of obliquely evaporated Co-CoO tapes has been investigated. A preferred orientation relation hcp-Co (001)//CoO (111) is found in the neighboring grains when the hcp-Co grains grow on top of the CoO. However, no preferred orientation is observed in the lower to middle part of the magnetic layer when the CoO grains grow on top of the hcp-Co. The structural properties of the Co-CoO tapes can be explained accordingly based on the preferred orientation relation. [ABSTRACT FROM AUTHOR]

The magnetic microstructure in a Co-CoO obliquely evaporated tape that was subjected to a recording bit length of 250 nm was studied using electron holography. The reconstructed phase image demonstrated a periodic pattern of magnetic flux loops that were inclined to the film normal due to a well-developed columnar structure. When a magnetic field was applied to the tape for observing the remanent state by holography, the periodic pattern of the flux loops gradually disappeared. Interestingly, on applying a large magnetic field, the contour lines in the reconstructed phase image became approximately parallel to the longitudinal axis of the sliced tape, i.e. the contour lines were made to virtually deviate from the easy magnetization axis. The observations were supported by a computer simulation in which the effect of the stray magnetic field was considered. [ABSTRACT FROM AUTHOR]