Thickness dependence of domain walls on Co thin films

Magnetization states of Co thin films were observed in a magnetic field by Bitter method, using a scanning laser microscope. Thick Co films had much number of domain walls than thin ones. In a demagnetization process at magnetic fields from 550 to −550 Oe, domain walls disappeared gradually on the thin Co film (15 nm) and disappeared sharply on the thick Co film (47 nm). The slope of magnetization curve was gradual for the thin Co film and sharp for the thick Co film. Co thin films had a different magnetization process for the difference of thickness.