Low temperature thermomagnetic print for hard disk servo writing

Thermomagnetic print, proposed in the 1980’s, is expected to apply to hard disk drive servo writing. The print needs to be done after certification of media using magnetic head, so decomposition of lubricant on the media surface is the issue. Thermomagnetic print can be done at lower temperatures than Curie point, utilizing the small change of Hc by heating. But since the print should be done in short term to avoid thermal diffusion, the effective Hc is much higher than the static Hc. In the process, proposed in this article, the dynamic effect is suppressed. A part of the printing field is generated in a very short period, so the dynamic Hc at nonheated areas is also increased and the divergence of Hc is kept large enough. For the experiment, KrF excimer laser was used as the light source. Si mask was faced on the media with 0.5 μm spacing. For printing narrow pattern less than 1 μm in width on media of Hc 3.4 kOe, the optimum laser power was 90 mJ/cm2 and the optimum printing field was 3.1 kG including ...