Size-dependent frequency bands in the ferromagnetic resonance of a Fe-nanocube

Schäffer A. F., Sukhov A., and Berakdar J.

Journal of Magnetism and Magnetic Materials 438, pp 70 (2017)

Using full micromagnetic simulations we calculate the spectra of ferromagnetic resonance (FMR) for an iron (core-shell) nanocube and show that the FMR characteristics are strongly size dependent. For instance, for a 40 nm it is found that, in contrast to a macrospin picture, the spectrum of the iron nanocube possesses two bands centered around 0.4 T and ~0.1 T. The peaks originate from the surface anisotropy induced by the strong demagnetizing fields (DMFs) of iron. Further simulations reveal that for ~20 nm nanocubes the macrospin model becomes viable. Above 40 nm we find a broad band for FMR absorption. Our results point to possible interpretations of existing FMR experimental observations for the system studied here.

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