MAGNETOIMPEDÂNCIA COMO FERRAMENTA PARA A CARACTERIZAÇÃO MAGNÉTICA DE MICROFIOS AMORFOS / MAGNETOIMPEDANCE AS A TOOL TO INVESTIGATE THE MAGNETIC PROPERTIES OF MICROWIRES

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

The possibility of exploring the magnetic properties of amorphous microwires in technological applications has attracted the attention of the scientific community in the last years. Beyond, the magnetoimpedance effect has been established as a powerful tool to study these properties. In this work we show a study of the magnetic properties of Joule heated glasscovered amorphous microwires, CoFeSiB, under applied stress. The stress modifies the anisotropy and the domain structure of the sample being studied by the magnetoimpedance measurements and the FMR dispersion relations. It was established a method to determine the permeability from the magnetoimpedance measurements, valid for a wide frequency range. From the study of the permeability curves parameters associated to the domain walls dynamic can be determined. From the FMR dispersion relations, the value and the direction of the transverse anisotropy field, as well as an estimative of the magnetic domain structure in these microwires were obtained. It can be concluded that the longitudinal anisotropy has the main role in the magnetic behavior of the microwire without stress. Also, it was verified the presence of an inner core with longitudinal anisotropy surrounded by an outer shell with circumferential anisotropy under applied stress. These magnetic configurations can be explained in terms of the frozen stress in the production process of the wire and the additional applied stress.

ASSUNTO(S)

ressonância ferromagnética ferromagnetic resonance impedance joule heating microfios amorfos aquecimento joule estrutura de domínios impedância amorphous microwires fisica domain structure

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