Superferromagnetism in chain-like Fe@SiO2 nanoparticle ensembles

One-dimensional (1D) chain-like nanocomposites, created by ensembles of nanoparticles of with diameter ∼ 13 nm, which are composed of an iron core (∼4 nm) and a silica protective layer, were prepared by a self-assembly process. Chain-like Fe@SiO2 ensembles were formed due to strong magnetic dipole–d...

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Bibliographic Details
Published in:Journal of applied physics 2014-07, Vol.116 (3)
Main Authors: Zeleňáková, A., Zeleňák, V., Mat'ko, I., Strečková, M., Hrubovčák, P., Kováč, J.
Format: Article
Language:English
Subjects:
Absorption spectra
Applied physics
Coercivity
Cooling
Core making
Dipole interactions
Iron
Magnetic dipoles
Magnetic moments
Magnetism
Nanocomposites
Nanoparticles
Oxidation
Process management
Self-assembly
Silicon dioxide
Temperature dependence
X ray spectra
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Summary:One-dimensional (1D) chain-like nanocomposites, created by ensembles of nanoparticles of with diameter ∼ 13 nm, which are composed of an iron core (∼4 nm) and a silica protective layer, were prepared by a self-assembly process. Chain-like Fe@SiO2 ensembles were formed due to strong magnetic dipole–dipole interactions between individual Fe nanoparticles and the subsequent fixation of the Fe particles by the SiO2 layers. X-ray near edge absorption spectra measurements at the Fe K absorption edge confirm that the presence of a silica layer prevents the oxidation of the magnetic Fe core. Strong magnetic interactions between Fe cores lead to long-range ordering of magnetic moments, and the nanoparticle ensembles exhibit superferromagnetic characteristics demonstrated by a broad blocking Zero-field cooling (ZFC)/field-cooling distribution, nearly constant temperature dependence of ZFC magnetization, and non-zero coercivity at room temperature. Low room-temperature coercivity and the presence of electrically insulating SiO2 shells surrounding the Fe core make the studied samples suitable candidates for microelectronic applications.
ISSN:0021-8979
1089-7550
DOI:10.1063/1.4890354