Temperature dependence of magnetocrystalline anisotropy for Sn substituted Ba ferrite particles

Temperature dependence of magnetocrystalline anisotropy was measured for Co-Ti-Sn substituted Ba ferrite particles, to clarify the origin of a small temperature dependence of coercivity (dHc/dT) for this material. For comparison, the same measurement was carried out for Co-Ti substituted particles which have positive dHc/dT near room temperature. First and second anisotropy constants K₁ and K₂ were found to be both positive for these materials. In the Co-Ti-Sn particles, K₁ was dominant over K₂ over the whole temperature range, and K₁ decreased rapidly with increasing temperature. The rapid decrease in K₁ explains the experimental small dHc/dT. In the case of Co-Ti particles, K₂ is not negligible below 0°C. The decrease in Hc with increasing temperature for the Co-Ti particles at a low temperature range is due to the decrease in K₂. The predicted temperature dependencies of Hc derived by using the K₁ and K₂ values for the two kinds of materials explain the material results