Anomalous magnetic behaviour of Cr2O3-SiO2 nanocomposites

Santanu Bhattacharya, Sourish Banerjee, D. Chakravorty

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Abstract

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 Cr 3+ 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.

Original languageEnglish (US)
Article number095002
JournalJournal of Physics D: Applied Physics
Volume42
Issue number9
DOIs
StatePublished - May 7 2009
Externally publishedYes

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ASJC Scopus subject areas

  • Condensed Matter Physics
  • Electronic, Optical and Magnetic Materials
  • Acoustics and Ultrasonics
  • Surfaces, Coatings and Films

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