Teorias de Landau e da Perturbação Termodinâmica aplicada à materiais magnetodielétricos

Abstract

The possibility of using the properties of multiferroic materials for technological applications is extensive. Among them stand out those in which there is a strong connection between the electrical and magnetic properties, the so-called magnetoelectric ones, in which the polarization of such a material can be modified by the application of magnetic field, as well as the magnetization has influence of an external electric field. To study the part of linear interaction from the magnetoelectric effect, besides several measurement experiments, the development of a theory to explain such coupling present in these materials is also of great value. In this work a small study on magnetoelectric multiferroic materials was developed, using the thermodynamic perturbation theory and the Landau theory of a single phase system that has the magnetoelectric effect and, as an application of the theories, calculations were made to deduce an upper bound for the tensor elements of the respective effect in magnetodielectric materials, where it was observed that the most restrictive limit depends directly on the electrical and magnetic susceptibilities of the magnetoelectric medium, inducing, although not definitively because there are materials that fail in the developed result, that the substances with higher probabilities of showing a strong coupling of the studious nature are those that are both ferroelectric and ferromagnetic.