Role of dipolar interactions in a system of Ni nanoparticles studied by magnetic susceptibility measurements

• Autor(a) principal: Masunaga, Sueli Hatsumi
• Data de Publicação: 2009
• Outros Autores: Jardim, Renato de Figueiredo, Fichtner, Paulo Fernando Papaleo, Rivas, J.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UFRGS
• Texto Completo: http://hdl.handle.net/10183/117993
• topic: Propriedades magnéticas; Materiais ferromagnéticos; Nanopartículas

The role of dipolar interactions among Ni nanoparticles NPs embedded in an amorphous SiO2 /C matrix with different concentrations has been studied performing ac magnetic susceptibility ac measurements. For very diluted samples, with Ni concentrations 4 wt % Ni or very weak dipolar interactions, the data are well described by the Néel-Arrhenius law. Increasing Ni concentration to values up to 12.8 wt % Ni results in changes in the Néel-Arrhenius behavior, the dipolar interactions become important, and need to be considered to describe the magnetic response of the NPs system. We have found no evidence of a spin-glasslike behavior in our Ni NP systems even when dipolar interactions are clearly present.