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The magnetic and transport properties of a (g-Fe2O3) 80Ag20 nanocomposite, prepared by a reverse micelle technique, have been studied. g-Fe2O3 nanoparticles and Ag particles were individually synthesized in reverse micelles. The nanocomposite material was then prepared by mixing the two different particles in a g-Fe2O3/Ag molar ratio 80/20. The morphology of the nanoparticles was examined with transmission electron microscopy. Mssbauer spectra revealed no obvious presence of any divalent iron. Zero field cooled and field cooled magnetic susceptibilities indicated a blocking temperature of about 40 K. Negative magnetoresistance was observed resembling that in ball milled g-Fe2O3/Ag nanocomposites. However, the magnitude of the negative magnetoresistance is smaller and is;2.2% at 220 K and 9 T. Two possible mechanisms, spin-dependent hopping and tunneling across magnetic barriers, are discussed. ©2000 American Institute of Physics.



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