Magnetization pattern of ferromagnetic nanodisks

We explore the magnetization pattern of Co and permalloy disks with diamete rs between 80 nm and 1 mu m by using two complementary experimental techniq ues: Lorentz microscopy and magnetic force microscopy (MFM). By means of Lo rentz microscopy we show that the dominating magnetization pattern of the d isks is a vortex structure with closed flux lines in the plane of the disks . Complementary MFM measurements demonstrate that the magnetization in the center of the disks is tilted out of the plane of the disk. The experimenta l findings closely agree with corresponding micromagnetic calculations. (C) 2000 American Institute of Physics. [S0021-8979(00)02519-6].