Acoplamento spin-fônon no Ba1.6Sr1.4Co2Fe24O41

• Ano de defesa: 2015
• Autor(a) principal: Santos, Yvens Pereira dos
• Orientador(a): Macêdo, Marcelo Andrade
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Sergipe
• Programa de Pós-Graduação: Pós-Graduação em Física
• País: BR
• Palavras-chave em Português: Física; Ferromagnetismo; Spin-Fônon; Bário; Hexaferrita; Magnetismo
• Área do conhecimento CNPq: CNPQ::CIENCIAS EXATAS E DA TERRA::FISICA
• Link de acesso: https://ri.ufs.br/handle/riufs/5322

We present a study of the magnetic and structural propertiers of the multiferroic BaxSr(3-x)Co2Fe24O41, x = 0.4 1.6 produced by proteic sol-gel process. The crystalline structure of the samples was analyzed by X-ray diffractometry (XRD) and magnetization measurements were made using a vibrating sample magnetometer (VSM). All samples presented preferential orientation due to the sintering process. The Ba1.6Sr1.4Co2Z sample was systematically studied by Raman spectroscopy, monitoring the behavior of its spectrum in the range of ~300 to ~700 K and showed anomalous behavior of some vibrational modes that were associated with a spin-phonon coupling that allowed the identification of two of the sample changes in magnetic anisotropy and its Curie temperature (Tc). X-ray fluorescence study indicated the presence of Ba, Sr, Fe and Co in the expected proportion and a small quantity, of spurious elements. Magnetization measurements of the Ba1.6Sr1.4Co2Z evidenced the ferrimagnetic character of the sample and characteristic crystalline anisotropy making it a good candidate for application as sensors of magnetic field direction. The high electrical resistivity, found in Ba1.6Sr1.4Co2Z favors its use in electronic devices and facilitates applications of the magneteletric effect in electronic devices. The Rietveld refinement showed the presence of the majority Ztype hexaferrite phase, although traces of Y and W phases were detected that coexist with the Z phase in the temperature range used for the production of the samples.