Redes de vórtices e disclinações num estado supercondutor-nemático

• Autor(a) principal: Silva Júnior, Nei Lopes da
• Data de Publicação: 2016
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UERJ
• Texto Completo: http://www.bdtd.uerj.br/handle/1/12954
• topic: Nematic-superconductor; Vortex lattice and disclinations; Ginzburg-Landau Theory; Cuprates.; Estado supercondutor-nemático; Redes de vórtices e disclinações; Teoria de Landau-Ginzburg; Cupratos supercondutores; CNPQ::CIENCIAS EXATAS E DA TERRA::FISICA::FISICA DA MATERIA CONDENSADA

In order to contribute to the understanding of the complex phase diagram of the superconducting cuprates we present, in this master thesis, a new way of looking at the phenomenon of superconductivity. The phase diagram of several materials shows regions where different magnetic and charge orders coexist. In particular, in the underdoped region of cuprates, the system tend to form superconducting domains than break rotation invariance. Recently, the existence of a new state, in which the superconducting order coexists with an orientational order, was proposed to be relevant in the pseudo-gap region. This state, called nematic-superconductor, supports different topological defects, such as vortices and disclinations. Using a Ginzburg-Landau theory, we study the stability of vortices and disclinations lattice structures. We found that, while vortex tend to form triangular lattices, disclinations prefer a tetragonal symmetry arrange. Thus, since vortices are strongly tighten to disclinations, there is a competition that produce a structural phase transition between the triangular and the square lattice of the disclination-vortex array.