Contribution of Fe²⁺, Mn³⁺ and Fe³⁺ ions to the magnetic anisotropy of Mg_xMn_0.6Fe_2.4-xO₄

The temperature dependences of the saturation magnetization sigma _s and of the anisotropy K₁ were measured in single crystals of Mg_xMn_yFe_3-x-yO₄, 0<or=x<or=0.63, y approximately=0.6. The magnitude and temperature dependence of the anisotropy contributions H₁ of Fe²⁺, Mn³⁺ and Fe³⁺ ions in B sites were found. The values H₁(=K₁per ion) established close to 0K are H₁(Fe²⁺)=0.21₇ cm^-1 per ion, H₁(Mn³⁺)=-0.37₇cm^-1 per ion and H₁(Fe³⁺)=-0.05 cm^-1 per ion. From the experimental results it follows that in B sites of the spinel investigated, the ground state of the Fe²⁺ ion is a singlet, the first excited state is a doublet, and the energy separation between singlet and doublet levels is E_t=(1770+or-150) cm^-1.