Publication: Magnetic susceptibility studies of the spin-glass and Verwey transitions in magnetite nanoparticles
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2013-05-07
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American Institute of Physics
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Abstract
Magnetite nanostructured powder samples were synthesized by aging chemical method. Phase, structural, and magnetic properties were characterized. X-ray diffraction patterns showed cubic magnetite pure phase, with average crystallite size, < D >, equal to 40 nm. Susceptibility measurements showed the well-known Verwey transition at a temperature of 90 K. The decrease of Verwey transition temperature, with respect to the one reported in literature (125 K) was attributed to the low average crystallite size. Moreover, the spin-glass like transition was observed at 35 K. Activation energy calculated from susceptibility curves, with values ranging from 6.26 to 6.93 meV, showed a dependence of spin-glass transition on frequency. Finally, hysteresis loops showed that there is not an effect of Verwey transition on magnetic properties. On the other hand, a large increase of coercivity and remanent magnetization at a temperature between 5 and 50 K confirmed the presence of a magnetic transition at low temperatures.
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© 2013 American Institute of Physics.
Joint MMM-Intermag Conference (12.2013. Chicago)
The authors would like to acknowledge UACJ, CIMAV, and IMA for the support given to this research.