V. N. Nikiforov, Yu. A. Koksharov, S. N. Polyakov, A. P. Malakho, A. V. Volkov, M. A. Moskvina, G. B. Khomutov, V. Yu. Irkhin
Magnetic and structural properties of magnetite nanoparticles stabilized in polyvinyl-alcohol thin films are investigated by using X-ray diffraction (XRD), transmission electron microscopy (TEM), electron paramagnetic resonance (EPR) and static magnetometry techniques. The nanoparticles have well-defined crystallinity, and are superparamagnetic at room temperature. Their size distribution is characterized by the distinct log-normal law (with average diameters near 5-7 nm) and slight maximum near 70-80 nm. The EPR spectra and static magnetization data demonstrated pronounced anomalies in the interval between 130 K (corresponding to Verwey transition) and 200 K. The experimental data obtained can be understood on the basis of the half-metallic electronic structure, complex temperature behavior of the magnetic anisotropy, along with effects of "weak magnetic-electron" sublattice of magnetite.
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http://arxiv.org/abs/1302.3090
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