The origin of ferromagnetism in Fe-57-doped NiO
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Douvalis, A. P.
Jankovic, L.
Bakas, T.
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peer reviewed
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Journal of Physics-Condensed Matter
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The origin of ferromagnetism observed in 2 at.% Fe-57-doped NiO samples is investigated. A precursor was produced from the co-precipitation of stoichiometric Fe-57 and Ni nitrate solutions, and the 2% Fe-57-doped NiO samples were prepared by heating this precursor in air at temperatures between 673 and 873 K, for 1-25 h. X-ray diffraction, scanning electron microscopy, magnetization measurements and Fe-57 Mossbauer spectroscopy were used to study the properties of the prepared compounds. The samples are composed of crystalline nanoparticles with average sizes between 9 and 29 nm, depending on the heating conditions. Magnetization measurements show the appearance of room-temperature ferromagnetism for samples heated both at 673 and 873 K. The Fe-57 Mossbauer spectroscopy results indicate that this ferromagnetism is related to (NiFe2O4)-Fe-57 ferrimagnetic impurities for the samples heated at 873 K and to finite-size effects for the samples heated at 673 K. The Ni57Fe2O4 impurities interact magnetically with the antiferromagnetic Fe-57-doped NiO matrix and it is proposed that they result from a diffusion-type process of Fe-57(3+) ions during the heat treatment of the precursor.
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room-temperature ferromagnetism, magnetic-properties, mossbauer-spectra, nanocrystalline nife2o4, ferrite nanoparticles, nickel ferrite, thin-films, band-gap, semiconductors, spintronics
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<Go to ISI>://000250146700006
http://iopscience.iop.org/0953-8984/19/43/436203/pdf/0953-8984_19_43_436203.pdf
http://iopscience.iop.org/0953-8984/19/43/436203/pdf/0953-8984_19_43_436203.pdf
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en
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Πανεπιστήμιο Ιωαννίνων. Σχολή Επιστημών και Τεχνολογιών. Τμήμα Βιολογικών Εφαρμογών και Τεχνολογιών