Evolution With Temperature of the Magnetic Anisotropy of Ba Ferrite Particles

The magnetic anisotropy of pure and Co/Ti-doped Ba ferrite particles is analyzed through the veluation of the dependence on temperature of the constants of magnetocrystalline and shape anisotropy, which both are present in the platelet-like Ba ferrite paricles with hexagonal structure. In undoped Ba ferrite, the magnetocrystalline anisotropy constant is predominant on the conflicting sdhape anisotropy constant at all temperatures, which indicates that the magnetic anisotropy is uniaxial, with preferred direction along the c axis of the hexagonal particles. In doped particles, where the magnetcrystalline anisotropy is weakened by the ionic substitutions, while at high temperatures the magnetic anisotropy is substantially uniaxial with c as axis of easy magnetization, when the temperature decreases the shape anisotropy constant becomes larger than the magnetocrystalline anisotropy constant, and, consequently, the magnetic anisotropy is not uniaxial,but it presents multiple preferred directions for the magnetization.