Competing anisotropies in bcc Fe81Ni19/Co(001) superlattices

A magnetization reorientation transition has been observed in Fe81Ni19/Co(001) superlattices by means of magneto-optical Kerr effect and magnetic force microscopy measurements. The transition is driven by the variation of the interface density. First-principles calculations are combined with a linear stability analysis of the Landau-Lifshitz equation to clarify the mechanism that drives the transition. We are able to identify it as being driven by competing interface in-plane and uniaxial bulk out-of-plane anisotropies. The origin of the bulk anisotropy is attributed to tetragonal distortions experimentally observed in these superlattices.