Anomalous magnetic behaviour of Cr2O3-SiO2 nanocomposites

Bhattacharya, Santanu ; Banerjee, Sourish ; Chakravorty, D. (2009) Anomalous magnetic behaviour of Cr2O3-SiO2 nanocomposites Journal of Physics D: Applied Physics, 42 (9). 095002_1-095002_7. ISSN 0022-3727

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Nanocomposites containing Cr2O3 particles having dimensions in the range 13-35 nm dispersed in a silica matrix have been prepared by a chemical method. X-ray diffraction investigation and high resolution electron microscopy substantiate the formation of Cr2O3 particles. X-ray photoelectron spectroscopy studies show the presence of a small amount of CrO2. The samples exhibit ferromagnetic property below 300 K with the hysteresis loop showing an exchange bias. The latter is explained as arising due to exchange interaction between the spins associated with Cr3+ and Cr4+ ions. Dc electrical resistivity measurements were analysed by a small polaron hopping model confirming the presence of Cr4+ ions at the surface of the particles. At temperatures above 100 K the magnetic hysteresis loop shift was such that zero magnetization was observed only for the negative magnetic field. This was explained as being due to a disorder effect on the magnetic spins of Cr4+ ions.

Item Type:Article
Source:Copyright of this article belongs to Institute of Physics.
ID Code:65687
Deposited On:17 Oct 2011 10:39
Last Modified:17 Oct 2011 10:39

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