Estudo das ondas de spin em redes ferromagnéticas sob deformações

• Autor(a) principal: Andrade, Michel Rodrigues
• Data de Publicação: 2019
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Federal do Ceará (UFC)
• Texto Completo: http://www.repositorio.ufc.br/handle/riufc/47605
• topic: Ondas de spin; Modelo de Heisenberg; Ferromagnetismo; Deformações

This paper gives a qualitative and quantitative description of the excitations of magnons that appear in two-dimensional magnetic materials. First we will discuss the so-called Holstein-Primakoff and spin operator transformations that are boson-based tools. Being a powerful technique since, we can use second quantization formalism. With this in mind, it is possible to apply them to the Heisenberg model and show that the low-energy quasiparticle excitations that describe such a system are called spin waves, which are essential for research and applications in technology such as the study of improving spintronics. thus the development of information theory. Heisenberg’s Hamiltonian is a primordial tool used in the construction of our problems, where we apply it to an infinite square ferromagnetic grid, initially under the effects of interactions between first and second neighbors and soon after in the application of lattices deformations such as simple deformations and shear only with first neighbor interactions to observe the effects on the energy spectrum.