Thin-film superparamagnetic resonance in a γ-Fe2O3 nanoparticle array

We have investigated the microwave properties of monodisperse, superparamagnetic γ-Fe2O3 nanoparticle arrays using broadband ferromagnetic resonance. We identify a novel field for resonance relationship in the films. Compared with ferromagnetic films of equal magnetization, resonance frequencies are...

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Bibliographic Details
Published in:Journal of applied physics 2008-04, Vol.103 (7)
Main Authors: Zohar, S., Hultman, K., O’Brien, S., Bailey, W. E.
Format: Article
Language:English
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Summary:We have investigated the microwave properties of monodisperse, superparamagnetic γ-Fe2O3 nanoparticle arrays using broadband ferromagnetic resonance. We identify a novel field for resonance relationship in the films. Compared with ferromagnetic films of equal magnetization, resonance frequencies are suppressed for in-plane magnetization and enhanced for out-of-plane magnetization, over the range of 0–8Ghz. The behavior identified is that of a superparamagnetic thin film, where thin-film dipolar fields act on a gradually saturating magnetization described by the Langevin function. Resonance linewidths can be described by the natural thermal dispersion in properties of the system.
ISSN:0021-8979
1089-7550
DOI:10.1063/1.2829392