Modelo de Stoner-Wohlfarth modificado aplicado a filmes finos

Abstract

The work at hand deals with the magnetization process of magnetic thin films wich possess only one magnetic layer. In order to describe this process we use the Stoner-Wohlfarth model of coherent rotation (model known as the simplest model of magnetization to exhibit magnetic hysteresis) modified. We choose to include in the more general free magnetic energy density the followings anisotropys: the uniaxial magnetic anisotropy induced during deposition process of the film, the magnetoelastic and the cubic magnetocrystalline anistropy - aside the shape anisotropy of the film which is implicit. We also consider the presence of dispersion of these anisotropies over the film to better fit the experimental curves. The magnetization curves were obtained via numeric minimization of energy density with respect to the film’s magnetization, and the minimization was carried through algorithm written in C language to this end. A com- parison between theoretical magnetization curves of films with and without anisotropy disper- sion was made. As a result, we verified some differences between curves of a disperse system and curves of the same system with no dispersion. The curves differ also in coercivity e mag- netic remanence. At the end, to test the modified Stoner-Wohlfarth model, we generate mag- netization curves considering a film with induced uniaxial anisotropy only and compare those curves with experimental ones of Py/Ag/Ag e Py/SnTe/Ag films over rigid substrates with the same anisotropy. We arrive at the conclusion that the model does not describe the experimental curves with accuracy, but is useful as a first approximation to the experimental magnetization curves considered.