2.5-inch disk patterned media prepared by an artificially assisted self-assembling method

Circumferential magnetic patterned media were prepared on a 2.5-inch-diameter glass plate and on a 3-in-diameter silicon plate. A Ni master disk possessing spiral patterns with 60-250-nm-width lands and a 400-nm-width groove was pressed into a resist film on a CoPt or CoCrPt film to transfer the spiral patterns. A diblock copolymer solution was cast into the obtained grooves and then annealed to prepare self-assembling dot structures aligned along the grooves. According to the dot patterns, the underlying magnetic films were patterned by ion milling to yield patterned media with a 40-nm diameter. Coercive forces and squareness ratios of the patterned media increased compared to those of the continuous media, probably due to the decrement of a demagnetizing field. Single magnetic domains with an almost perpendicular orientation were confirmed in each magnetic dot.