Exchange Interactions and Curie Temperature of Ce-Substituted SmCo5

Abstract

A partial substitution such as Ce in SmCo 5 could be a brilliant way to improve the magnetic performance, because it will introduce strain in the structure and breaks the lattice symmetry in a way that enhances the contribution of the Co atoms to magnetocrystalline anisotropy. However, Ce substitutions, which are benefit to improve the magnetocrystalline anisotropy, are detrimental to enhance the Curie temperature ( T C ). With the requirements of wide operating temperature range of magnetic devices, it is important to quantitatively explore the relationship between the T C and ferromagnetic exchange energy. In this paper we show, based on mean-field approximation, artificial tensile strain in SmCo 5 induced by substitution leads to enhanced effective ferromagnetic exchange energy and T C , even though Ce atom itself reduces T C .