Exchange interactions and curie temperature of ce-substituted SmCo5

Abstract

A partial substitution such as Ce in SmCo5 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 (TC). With the requirements of wide operating temperature range of magnetic devices, it is important to quantitatively explore the relationship between the TC and ferromagnetic exchange energy. In this paper we show, based on mean-field approximation, artificial tensile strain in SmCo5 induced by substitution leads to enhanced effective ferromagnetic exchange energy and TC, even though Ce atom itself reduces TC.