Solução de problemas padrão por meio de simulação micromagnética

Abstract

Until the practical use of magnetism on an industrial scale, as applied in our electronic devices, it is essential to know or predict the behavior of magnetic properties and quantities. In this context, micromagnetic simulation presents itself as an indispensable tool in this research process, which will later be meticulously validated and improved through laboratory techniques. To contribute to the theoretical framework in the field of micromagnetism research, our group, called the Condensed Matter Physics Group (CMPG), with a focus on micromagnetic simulation, has been dedicated for at least half a decade to the writing and constant improvement of our own software written in Fortran 90 programming language to analyze the temporal evolution of magnetization in discretized systems. These systems can be one-dimensional (nanowires), two-dimensional (planar or curved nanoribbons), or three-dimensional (bulks). Currently, the program already includes exchange interactions, anisotropy, external field, Dzyaloshinskii-Moriya interaction, and dipolar interaction, which makes it highly competitive compared to well-established simulators that use the demagnetizing field, in addition to already being capable of working with spin-polarized currents. The main proposal of this work is to solve the so-called standard-problems in micromagnetism to validate the software and give it more credibility in new research in this field. We are dedicated to studying the influence of a spin-polarized current on magnetic vortices in Permalloy-79 cuboids, as well as investigating the static cases of skyrmions and antiskyrmions in one-, two-, and three-dimensional systems. Our results have shown great agreement with the expected values, which indicates that both the discretization method; the treatment by dipolar interaction as an alternative to the demagnetizing field and the numerical resolution of the equation of motion governing micromagnetism (Landau-Lifshitz-Gilbert) are being correctly implemented.