Y.IVANOV, A.ILYIN, E.POUSTOVALOV, L.CHEBOTKEVICH

The research concerns magnetization reversal processes of nanodisk arrays with various array periods, the nanodisks being formed on 10 nm polycrystalline cobalt films. Magnetic hysteresis loops from a nanopoint array have been obtained by different methods exploring the magneto-optical longitudinal Kerr effect as well as the representation of magnetic structures and hysteresis loops from singular nanopoints by the magnetic force microscopy (MFM) method. Each nanopoint shows induced uniaxial magnetic anisotropy. It has been determined that an external magnetic field orientation relative to array faces has a profound impact on magnetization reversal processes. A dipole-dipole nanopoint interaction along the square array diagonal is less significant than that along its face, which results in collective behavior of magnetic spins in adjacent points. Micromagnetic modelling demonstrates magnetic whirls of opposite chirality in adjacent nanodisks in the centre of the array, while towards its edges there appear whirls of the same chirality, their nuclei being on the opposite nanodisk edges. MFM investigations of magnetic structures and micromagnetic modelling have shown asynchronism of magnetic structure changes resulting from magnetization reversal. The whirls arise first in the nanodisks arranged closer to the top of a square nanodisk array, then on array faces transverse to an applied field, and further in the array centre. On magnetization reversal of array data in a coercive force field, magnetic spins in all nanodisks are found to be polarized so that the total magnetic moment is equal to zero.