Estudo das propriedades magnetotérmicas e de transporte em intermetálicos contendo terras raras

Detalhes bibliográficos
Ano de defesa: 2017
Autor(a) principal: Souza, Marcos Vinicios de
Orientador(a): Plaza, Edison Jesus Ramirez
Banca de defesa: Não Informado pela instituição
Tipo de documento: Tese
Tipo de acesso: Acesso aberto
Idioma: por
Instituição de defesa: Não Informado pela instituição
Programa de Pós-Graduação: Pós-Graduação em Física
Departamento: Não Informado pela instituição
País: Não Informado pela instituição
Palavras-chave em Português:
Área do conhecimento CNPq:
Link de acesso: http://ri.ufs.br/jspui/handle/riufs/9009
Resumo: In this work we concentrate our efforts to obtain an algebraic relation capable of connecting the magnetic component of the caloric magneto potential, the magnetic entropy variation with the magnetic resistivity variation of the anisotropic magneto caloric compounds of the series RAl2, (R: rare earth). For this purpose, we use the single ion model, considering the approximation of the molecular field based on the interaction of long-range cooperative exchange to represent the magnetic interactions present in these compounds, through the Hamiltonian model. While the study of the resistive properties was carried out based on the dispersive dipole interaction between the conducting electrons and 4f located. This analytical and self consistent process results in ()-T e ()-T curves, which are compared to experimental data available in the literature. The comparison between these quantities, for the different crystallographic directions of the monocrystalline compounds RAl2, lacks the inclusion of a correlation factor that involves a power relation (T/Tc)m, whose exponent varies according to the thermal conditions and anisotropic. That is, for the compound HoAl2, for example the validity of the expression −=− is guaranteed by using the index m = 0.1 for region 0<T<Tc where the spin reorientation occurs, and for region that happens Tc the index m = 0.0 (direct ratio) must be used. This procedure was also used to describe the properties of the compounds TmAl2, DyAl2 and NdAl2, providing valuable information about the relationship between the variation of magnetic entropy and the variation of magnetic resistivity.