Abstract
This work takes advantage of Magneto-optical Kerr Effect (MOKE) to study the magnetic properties of 50-nm-thick disks grown on the /Si (100) wafer. The diameters of disks were roughly from 100 m to 650 m, which were fabricated by means of e-beam lithography, sputtering deposition and lift-off process. Our results show that the changes of magnetization direction on disks during sweep of magnetic field conform to the previous results of researches that the magnetization component perpendicular to outer magnetic field does not exist and our disks have the characteristic of vortex state, but coercivity seems to have no direct relationship with size of disks. They are all between about 15 Oe and 40 Oe. In addition, signals of hysteresis loops from our MOKE system change linearly with the area of disks.