Interplay between magnetocrystalline and configurational anisotropies in Fe(001) square nanostructures

We fabricated a set of arrays of single-crystal Fe micron and submicron square elements on MgO using a focused ion beam apparatus. The squares have different size ($1\text{\ensuremath{-}}\ensuremath{\mu}\mathrm{m}$ and 500-nm side) and orientation with respect to the crystalline axes. The three patterns were magnetically characterized by means of magneto-optical Kerr effect microscopy/magnetometry, and the symmetry and strength of their magnetic anisotropy was determined through transverse susceptibility measurements performed with the modulated field magneto-optical anisometry technique. We observed that the overall anisotropy of the systems is determined by the interplay between the intrinsic magnetocrystalline anisotropy of the material and the anisotropic energy of the magnetic configurations determined by the lateral confinement (the so called configurational anisotropy). Depending on the relative orientation of the patterns with respect to the intrinsic magnetocrystalline anisotropy axes, the interplay can give rise to enhancement or reduction of the configurational contributions compared to the case of identical patterns made of isotropic material. Our results demonstrate that the strength of the latter contribution is comparable to the first one and can be used to create nanoelements with peculiar anisotropy symmetries.