Magnetic Domain Observation and Magnetization Reversal Process in Patterned Films

The switching field distribution (SFD) and magnetization switching process in patterned films were studied by a magnetic force microscopy (MFM). CoPt patterned film (10 nm in height, 50 nm in diameter and 120 nm pitch) was fabricated by electron beam lithography and ion milling process. Co nanorod film was prepared by alumina anodic oxidation and successive electro-deposition. The coercivity of each dot was obtained by NUM measurements. Statistic as well as spatial distribution of switching field is analyzed by taking account of magnetic dipole interaction from surrounding dots (more than 50%) and intrinsic SFD of material itself. In both patterned films, the soft magnetic region causes a reduction of coercivity from ideal values through soft/hard exchange coupling.