Electronic Transport and Magnetic Properties of Co/SiO2 Magnetic Nanocomposites

Electric, thermoelectric, and magnetic properties of the magnetic nanocomposite (MNC) Co/SiO2 consisting of nanometer‐size Co nanoparticles embedded in SiO2 dielectric matrix have been studied. MNC is obtained in the form of (0.8–2.3) μm thick films with Co concentration 31.7–65.4 at.% by the electr...

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Bibliographic Details
Published in:physica status solidi (b) 2019-11, Vol.256 (11), p.n/a
Main Authors: Radchenko, Mykhailo, Lashkarev, Georgii, Baibara, Oleksii, Bugaiova, Maryna, Stelmakh, Yaroslav, Krushynska, Larysa, Foltyn, Marek, Knoff, Wojciech, Story, Tomasz, Nedelko, Natalia, Ślawska‐Waniewska, Anna
Format: Article
Language:English
Subjects:
Co nanoparticles
magnetic moment
magnetic nanocomposites
magnetothermoelectric power
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Summary:Electric, thermoelectric, and magnetic properties of the magnetic nanocomposite (MNC) Co/SiO2 consisting of nanometer‐size Co nanoparticles embedded in SiO2 dielectric matrix have been studied. MNC is obtained in the form of (0.8–2.3) μm thick films with Co concentration 31.7–65.4 at.% by the electron beam physical vapor deposition method on polycrystalline Al2O3 substrates. The temperature dependence of the resistivity follows the Mott law. The negative magnetothermoelectric power discovered in MNC Co/SiO2 can be explained by hopping conductivity through the magnetic localization centers in the SiO2 matrix or chemical interaction of Co with Si and O2, which results in a mixture of CoSi (ferromagnetic) and CoO (antiferromagnetic) phases. As the cobalt concentration increases, the particle size increases and the interparticle distances decrease. This is confirmed by the magnetic behavior of the sample with high Co concentration, which is dominated by large Co nanoparticles and strong interparticle magnetic interactions. The structure and the electric, magnetic and thermoelectric properties of the magnetic nanocomposite Co/SiO2 have been studied. Negative magnetothermoelectric power has been discovered. The explanation is related to the conductivity mechanism in the magnetic nanocomposite and its structure. It is shown that structural imperfections (such as defects in the Co nanocrystals, magnetic size distribution, phase intermixing) have additional impact on the magnetic properties.
ISSN:0370-1972
1521-3951
DOI:10.1002/pssb.201900145