Effect of exchange and crystal fields on temperature dependence of SM3+magnetization

In Sm³⁺ion the energy separation between the ground multiplet level and the first excited multiplet level is small and therefore the exchange and crystal fields can considerably admix these levels. As a result of this admixture by exchange fields alone, the Sm³⁺magnetization in magnetically ordered compounds changes sign or shows a crossover at a temperature of about 300 K. Thus in samarium compounds with transition elements, where the transition element has a moment, the samarium moment couples parallel to transition element moment below 300 K and antiparallel above 300 K. We have investigated the effects of crystal fields (of hexagonal symmetry) on Sm³⁺magnetization and find that the crossover temperature in magnetization is considerably altered by crystal fields (and also by exchange fields in the presence of crystal fields) from the value of 300 K for free Sm³⁺ion. The magnetization results on SmCo5are discussed in the light of these calculations.