Symmetry breaking effects in epitaxial magnetic thin films: Nonsymmetric reversal and butterfly remanence behavior

Abstract

A consistent picture which explains the effects of magnetic anisotropy symmetry breaking on the magnetic properties of epitaxial magnetic thin films is provided, including experimental results in ${\ensuremath{\gamma}}^{\ensuremath{'}}\text{\ensuremath{-}}{\mathrm{Fe}}_{4}\mathrm{N}(100)$ thin films and numerical simulations. As expected for a thin film with fourfold crystal symmetry, the results show the existence of two easy and two hard magnetization axes. However, in this case, the easy axes are not orthogonal, the hard axes are not equivalent, the magnetization reversal behavior around the two easy axes is not symmetric, and the reversal behaviors of the two hard axes are not alike. As a consequence, the polar plot of the remanence displays a butterfly shape behavior. These effects depend on additional terms of the magnetic anisotropy. Our results are extended to other symmetry breaking epitaxial magnetic systems.