Abstract
To examine the kind and the origin of magnetic anisotropy in γ-Fe2O3 particles, cobalt-epitaxial iron oxides and cobalt-doped iron oxides, the temperature variation of coercivity and magnetic torque was measured for the magnetic sheets prepared by using the oxide particles. The magnetic anisotropy of y-Fe2O3 particles was a uniaxial anisotropy due to the shape anisotropy. The main magnetic anisotropy of cobalt-epitaxial iron oxides was also uniaxial anisotropy, which was expected to be induced in cobalt-ferrite when the cobalt-ferrite was crystallized on the surface of γ-Fe2O3 particles. The coercivity of cobalt-doped iron oxides was nearly based on the crystalline magnetic anisotropy. The crystalline magnetic anisotropy energy showed a remarkable variation for temperature, compared with the uniaxial anisotropy energies of γ-Fe2O3 particles and cobalt-epitaxial iron oxides.
