Coercivity global model and magnetization reversal in fine hexaferrites

In this work, the so‐called global model for magnetization reversal is applied to describe the coercive field temperature dependence in fine barium and strontium M‐hexaferrites (75–300 K range). Using magnetic viscosity measurements, the temperature dependence of the activation volume for magnetization reversal was obtained. In this temperature range, the coercive field (as the anisotropy field) increases with increasing temperature. However, it is found experimentally that the activation volume also increases with temperature and then the physical interpretation of the model is partially not clear.