Magnetocrystalline anisotropy of tetragonal phase CuFe2O4

A small twinned crystal of tetragonal phase CuFe24was obtained, in which tetragonal c axes are almost equally distributed along only two perpendicular directions (taken as Y and Z axes of the crystal). Magnetic torque measurements were made on a small spherical sample (0.63 mm in diameter) at room temperature, 77 K and 4.2 K, and in magnetic fields up to 21 kG. Expressing the uniaxial anisotropy energy (Eu) as , and K3were found to equal -8.9 × 10⁵, 11.4 × 10⁵and -8.5 × 10⁵ergs/cc, respectively, at 4.2 K. Their absolute values decrease linearly with temperature. The direction of easy magnetization is not parallel to the c axis but is inclined at about 60°. This inclination is almost independent of temperature.