Up to now, we have presented a variational method based on the
minimization of the free energy of a ferromagnetic body. This
method allows one to find the equilibrium configurations for a
magnetized body, regardless of describing how magnetization
reaches the equilibrium during time. Recently, the challenging
requirements of greater speed and areal density in magnetic
storage elements, has considerably increased the effort of the
researchers in the investigation of magnetization dynamics. Most
of the analysis are based on the dynamic model proposed by Landau
and Lifshitz [3] in 1935, and successively modified by
Gilbert [18] in 1955. In this section we will present
both Landau-Lifshitz and Gilbert equations as a model for
magnetization `motion'. The differences between them are
emphasized and the properties of magnetization dynamics are shown
in view of the discussions and results presented in the following
chapters.
Subsections
