In this thesis, we present a phenomenological model to describe the behavior of magnetization and free energy with and without the participation of an external field. The derivation of the free energy is developed in the frame of Landau theory based on symmetry requirements. Our mechanism demonstrates that the external field can not only decrease the free energy but induce the emergence of the uniform magnetization in the same direction of the external field. In addition, when the external field enhances to a critical value, the original spiral component vanishes and the formation of the free energy changes into another form that can decrease the energy much more. This model would be useful to predict how the magnetization affected by an external field.