Algumas propriedades de ondas eletromagnéticas confinadas a guias de ondas constituídos por interfaces de isolantes topológicos

• Autor(a) principal: Melo, Thiago Martins
• Data de Publicação: 2011
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/4252
• topic: Isolante; Topológico; Guias; Ondas eletromagnéticas; Insulation; Topology; Guides; Electromagnetic waves; CNPQ::CIENCIAS EXATAS E DA TERRA::FISICA::FISICA DA MATERIA CONDENSADA

In recent years the concept of topological order has been widely used to classify electronic phases of matter, like phases that present the quantum Hall effect. This effect manifests itself in materials which present strong spin-orbit interaction, leading to phases named topological insulators. A topological insulator, as well as a common insulator, have the valence and conduction bands separated by an energy gap, but allow border states with no energy gap at both ends. In this dissertation, we review the main properties of such materials, as their band structure and the topological classification that distinguishes them from trivial insulators. Because the surface of these materials exhibit states with no energy gap, it leads to a non-zero Hall conductivity at the boundaries, where the manifestation of topological magneto-electric effect occurs, which, in turn, is described by a term that couples the electric and magnetic fields, with a kind of axion field θ which has a value equal π for topological insulators and a null value for non-topological insulators. The magneto-electric topological effect changes some fundamental properties in the electromagnetic waves propagation, as the Kerr and Faraday rotation and the Brewster s angle. Besides being possible to obtain the electromagnetic response quantization in terms of fundamental constants units, like the fine structure constant. In this dissertation, we studied the effects of electromagnetic waves confinement to waveguides, whose walls are made of topological insulators. First we deal with the rectangular waveguide, obtaining the wave equations, the transverse components of the electric and the magnetic fields and the spatial dynamics of the field axial components in this system. Later, we studied in a more detailed way a specific type of waveguide, called slab waveguide, which simplifies the propagation of electromagnetic waves analysis due to the simplicity of some equations in this system, and relate them to the non-trivial boundary conditions, originated from the topological magneto-electric effect. Finally, we compare the results with some well-known waveguides from the literature.