No abstract

The duplication characteristics of perpendicular magnetic media were analyzed by using metal evaporated (ME) tape as a slave medium. In the case of bit printing (BP), the best duplication characteristic was obtained at a duplication field of 4 kOe, about 2 times higher than the coercivity of the ME tape. On the other hand, in the case of edge printing (EP), duplication characteristics were saturated when the duplication field was more than 3kOe. When the duplication field was strengthened, in the case of BP, the peak position shifted towards the outside of the magnetic layer of the master, whereas, in EP, the peak position shifted towards the center of the magnetic layer. The calculated MFM output waveform obtained by using computer simulation almost coincided with the experimental result, and the cause of the sub-peak could thus be explained. It was concluded that EP has better duplication characteristics than BP.

A perpendicular anisotropy master medium (PAMM) is proposed. The PAMM is composed of CoPt film with perpendicular magnetic anisotropy and large saturation magnetization. The magnetization distributions of PAMM and conventional master media (using an FeCo soft magnetic layer) were analyzed by using micromagnetic simulation. It was found that the peak-to-valley value of the recording field and the recording field gradient at the edge of the patterned magnetic film of PAMM were larger than those of the conventional master medium. Furthermore, the peak-to-valley value of the recording field and the recording field gradient of PAMM did not depend on the strength of the printing field. The printing characteristic of PAMM is twice that of the conventional master medium. Furthermore, the optimum printing field for PAMM is 1 kOe lower than that of the conventional master medium. As a result, PAMM is expected to improve the printing characteristic of the bit printing method.

A master pattern with the a line-and-space (L/S) part and a checker part in the servo signals was made by using an FeCo film, and the edge printing characteristics of both parts were compared. The MFM output in the checker part was equal to the L/S part for a bit length of 200 nm, while for a bit length of 100 nm, the MFM output in the checker part decreased by about 30％ compared with that in the L/S part, because of the MFM 's low resolution. However, for a bit length of 100 nm, simulation results showed that the edge-printed magnetization of the checker part was equal to that of the L/S part. When the TMR head reproduced both parts, the output in the checker part was equal to that in the L/S part. The optimum printing field for the checker part was the same as that for the L/S part. Moreover, the rate of decrease in the MFM output did not depend on the printing field.