Relaxação de spin: principais mecanismos em microfios e em filmes multicamadas

Detalhes bibliográficos
Ano de defesa: 2010
Autor(a) principal: Sossmeier, Kelly Daiane
Orientador(a): Não Informado pela instituição
Banca de defesa: Não Informado pela instituição
Tipo de documento: Tese
Tipo de acesso: Acesso aberto
Idioma: por
Instituição de defesa: Universidade Federal de Santa Maria
BR
Física
UFSM
Programa de Pós-Graduação em Física
Programa de Pós-Graduação: Não Informado pela instituição
Departamento: Não Informado pela instituição
País: Não Informado pela instituição
Palavras-chave em Português:
Link de acesso: http://repositorio.ufsm.br/handle/1/3889
Resumo: This work is dedicated to investigate the spin relaxation in amorphous CoFeSiB glass-covered microwires and multilayered films of Permalloy/Cu. The microwires samples were Joule annealed and axially stressed in order to evaluate the modifications in the damping mechanisms due to the stress induced anisotropy. In the films we were interested in the observation of the modifications in the damping mechanisms imposed by the number of interfaces in the samples. We were able to identify the main damping mechanisms responsible for the spin relaxation in these materials by ferromagnetic resonance experiments. In order to explain the ferromagnetic resonance linewidth, we considered the extrinsic magnetic relaxation mechanisms in addition to the intrinsic Gilbert damping term, the intrinsic one. The extrinsic magnetic relaxation takes in to account the broadening induced by the magnetic inhomogeneities and is consistent with the two-magnon scattering model and anisotropy dispersions. The contribution from the intrinsic magnetization relaxation is constant in both systems of samples and is not sensible neither to Joule annealing and applied stress in microwires, nor to the increasing of the bilayers number in the films. The extrinsic contribution is very sensible to the anisotropy induction and is a signature of magnetic and structural inhomogeneities.