Effect of Cr3+ ions on the magnetic moment of ferrites of the system CuFe2−x CrxO4

The dependence of the magnetic moment n _0exp of samples of the system CuFe_2−x Cr_xO₄ (x=0.0, 0.2, 0.3, 1.0, 1.4, 1.6, and 2.0) on their Cr³⁺ content is examined here for the first time. It is found that the experimental values of the magnetic moment n _0exp are much smaller than the values calculated from the cation distribution obtained previously (n _{0 theor}). It is suggested that this relationship (n _{0 theor}>n _{0 exp}) is due to a decrease in the magnetic moments of the Cr³⁺ ions resulting both from pairing of the t _2g orbitals of these cations in the octahedral sublattice and from a transfer of spin density from the ligands to the e _g orbitals of these ions. For compositions with x>1.0, the noncollinear magnetic structure also leads to an increase in the difference between n _{0 theor} and n _0exp. Fiz. Tverd. Tela (St. Petersburg) 40, 99–100 (January 1998)