Avaliação da anisotropia magnetica de filmes finos por ressonancia ferromagnetica

AUTOR(ES)
DATA DE PUBLICAÇÃO

2002

RESUMO

Magnetic anisotropies of thin films are analysed from Ferromagnetic Resonance spectra obtained for different orientations of the samples with respect to the applied magnetic field. An Fe monocrystalline film, a Co polycrystalline film, a Co/Pd multilayers set of films with Co layers 3, 4 and 6Å thick with 15Å Pd as spacer layers, and a set of granular Co-Cu films with different compositions (10% and 30% Co) submitted to different thermal treatments are studied. Besides magnetic anisotropies, which are presented by all the samples, other characteristics of the films are discussed. The monolayer samples of Fe and Co permitted the study of typical Ferromagnetic Resonance spectra of thin films and of its dependence on the sample crystallinity. From the Co/Pd multilayers it is possible to observe a tendency of a magnetic easy axis changing towards the film plane normal, as one considers the samples with the thinnest Co layers. The presence of at least two resonance modes in the spectra is also observed. For the granular films one observes superparamagnetic mode in the 10% Co samples and spin wave modes in the 30% Co ones, besides the alterations in the magnetic behaviour caused by the thermal treatment. The spectral parameters are obtained straightforwardly from the experimental data using Lorentzian curves. A model based in the magnetic field orientation dependent part of the system free energy is used to the analysis of the magnetic behaviour of the films. Some magnetic properties, as the anisotropy constants of the films, are obtained using the same model. The obtained set of results shows the high sensitivity and the versatility of the technique in the thin films study aiding in the description of the large range of physical phenomena related to the new magnetic materials with possibilities of technological application

ASSUNTO(S)

filmes metalicos filmes finos - propriedades magneticas ressonancia magnetica anisotropia

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