The Effect of Hydrostatic Pressure on the Magnetic Anisotropy of Ferrous and Ferric Ions in Ferrites with Spinel Structure

The first order magnetic anisotropy constant K 1 of eight ferrites with inverse-type spinel structure and two ferrites with normal-type has been measured under hydrostatic pressure by the use of a torque method. The pressure dependence of K 1 , K 1 -1 ( d K 1 / d p ), in Li 0.5 Fe 2.5 O 4 is +4.1×10 -6 bar -1 , in NiFe 2 O 4 is +3.3×10 -6 bar -1 , in Li 0.05 Fe 2.95 O 4 is -18.0×10 -6 bar -1 , in Fe 3 O 4 is -13.5×10 -6 bar -1 , in Fe 2.96 Ti 0.04 O 4 is -9.4×10 -6 bar -1 , in Fe 2.90 Ti 0.10 O 4 is -6.5×10 -6 bar -1 , in Fe 2.82 Ti 0.18 O 4 is -1.4×10 -6 bar -1 , in Fe 2.69 Ti 0.31 O 4 is +3.0×10 -6 bar -1 , in MnFe 2 O 4 is +7.0×10 -6 bar -1 , in Mn 0.8 Zn 0.2 Fe 2 O 4 is +6.0×10 -6 bar -1 at room temperature. The results are discussed with regard to a single-ion model. In spinel, the contribution of ferrous ion to anisotropy constant K 1 increases, and that of ferric ion decreases, with decreasing lattice constant under hydrostatic pressure.