Transições de fases quânticas em sistemas bidimensionais com anisotropia de plano fácil

Abstract

The study of quantum spin systems has a great interest in Condensed Matter Physics both from a theoretical and experimental point of view, and the study of low-dimensional magnetic models plays an important role in our understanding of phase transitions, critical behavior and in the physics of many-body systems. We will study magnetic systems in two dimensions with easy plane anisotropy. These systems have a quantum phase transition at zero temperature when we change the anisotropy parameter. We will use the SU(3) Schwinger boson formalism. We will study 3 models. In the first one, we will deal with the effect of the pseudo-dipolar interaction that leads to a Higgs mode. In the second, we will study coupled chains and compare them with experimental data.In the third problem we will analyze the effect of the Moryia-Dzialoshinskii interaction.