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1.3 PHYSICAL SCIENCES, 1.4 CHEMICAL SCIENCES
The magnetic and magnetotransport properties of nanoparticulate magnetite with different grain
sizes are investigated using x-ray diffraction, microscopy, magnetometry, and magnetoresistance
measurements. The magnetization varies significantly with grain size and is sensitive to preparation conditions. The reduction in saturation magnetization in coprecipitated particles is probably due to the surface spin disorder. Magnetoresistance of pressed powder compacts is significantly enhanced
in material composed of small grain size magnetite particles prepared by coprecipitation. Useful
magnetoresistance persists well above room temperature in sintered ceramic material.
M. Venkatesan, S. Nawka, S. C. Pillai and J.M.D. Coey, (2003) : Enhanced magnetoresistance in nanocrystalline magnetite, Journal of Applied Physics, 93, 2003, 8023-8025, May, 2003. doi:10.1063/1.1555371