Abstract
The maximum pinning force between a Bloch wall and a planar pinning site is calculated to depend linearly on K3/21/A1/21, where K1 and A1 are the anisotropy and exchange constants of the ferromagnet, and as a result the pinning force is, in general, a function of the temperature. The temperature dependence of the coercive field Hc(T) of a MnAlC permanent magnet is well described in a model that considers two factors; one is the temperature dependence of the height of the energy barrier that a domain wall has to overcome on breaking away from a pinning site, and the other is thermal energy which assists a domain wall to cross the energy barrier.