  A partial substitution of Sm by Ce can have drastic effects on 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, that Ce substitution-induced tensile strain in
SmCo5 leads to enhanced effective ferromagnetic exchange energy and TC while Ce
atom itself reduces TC.
