Anisotropy, magnetic domains and magnetization reversal of nanostripes and nanosquares patterned by atomic saw on epitaxial Fe layers

The use of dislocations as atomic saws has allowed us to obtain artificial magnetic systems with reduced lateral size. According to the deformation conditions, we have realised surface stepped film, nanostripes or nanosquares from thin epitaxial Fe layers deposited on (001) MgO substrate. We show that, concerning the stripes, a strong uniaxial magnetic anisotropy (ranging from 8 to 14 ×10⁵ erg/cm³) is surprisingly present with the in-plane easy axis perpendicular to the stripes. We demonstrate the role played by the relaxation of the elastic strain field at interfaces. In nanosquares, as the fourfold cubic symmetry is recovered, a particular magnetization reversal is now governed by nucleation phenomena with the appearance of 180 and 90 domain walls. «Checkerboard» domain patterns are observed by optical Kerr microscopy.