Exchange force explanation for the antiferromagnet-ferromagnet transition in dysprosium

An explanation based on exchange forces is proposed for the anti-ferromagnet-ferromagnet transition in Dy which is in good agreement with the available experimental results. Contrary to the usual idea that the driving mechanism is the magnetostriction and anisotropy in the basal plane of the HCP structure, it is shown that the exchange forces are mainly responsible for the transition. Magnetoelastic, anisotropy and applied magnetic field energies only provide the delicate balance of energy necessary to assist the exchange forces for the transition. These energies only amount to a relatively small fraction (< 20%) of the total driving energy. (author)