Magnetization reversal of nanodots with different magnetic anisotropy and magnetostatic energy

The arrays of circle and square nanodots were prepared by Ga+ ion-beam etching of thing cobalt films with induced uniaxial magnetic anisotropy. The size of researched nanodots was d=600, 450 and 250 nm that equal or less then radius of ferromagnetic correlation for continuous Co film. The distances l=2d and 3d between center of nanodots in the arrays were taken. The interpretation of experimental magnetic force microscopy data was done by means of micromagnetic simulation and MFM-experiment simulation. Each nanodot of arrays with d=600 nm has multidomain structure at demagnetisation state for l=3d and magnetic vortex for l=2d. For arrays with size of element d<600 nm and l=2d and 3d at same condition occurred only vortex state.