Abstract
Magnetic dot arrays were fabricated by using focused ion beam (FIB) lithography to pattern a continuous CoPt film with the aim of establishing design guidelines for patterned media with a soft magnetic underlayer. First, the magnetic influences of Ga ion irradiation were investigated in order to understand the characteristics of FIB milling. It was found that the implantation of Ga ions in the recording layer or the soft magnetic underlayer seriously affected the magnetic properties. Magnetic dot arrays were then fabricated, taking account of this effect. The switching field of the film drastically increased with the patterning and exhibited a further increase with decreasing dot size. The slope of the remanent magnetization curve decreased considerably as the dot spacing was decreased. The results suggest that patterned media should have a smaller dot size and larger spacing.
