  We propose a model for non isothermal ferromagnetic phase transition based on
a phase field approach, in which the phase parameter is related but not
identified with the magnetization. The magnetization is split in a paramagnetic
and in a ferromagnetic contribution, dependent on a scalar phase parameter and
identically null above the Curie temperature. The dynamics of the magnetization
below the Curie temperature is governed by the order parameter evolution
equation and by a Landau-Lifshitz type equation for the magnetization vector.
In the simple situation of a uniaxial magnet it is shown how the order
parameter dynamics reproduces the hysteresis effect of the magnetization.
