Nano Archive

Control of Magnetism in Cobalt Nanoparticles by Oxygen Passivation

Srikala, D. and Singh, V. N. and Banerjee, A. and Mehta, B. R. and Patnaik, S. (2008) Control of Magnetism in Cobalt Nanoparticles by Oxygen Passivation. JOURNAL OF PHYSICAL CHEMISTRY C, 112 (36). 13882-13885. ISSN Print Edition ISSN: 1932-7447; Web Edition ISSN: 1932-7455

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Official URL: http://pubs.acs.org/doi/abs/10.1021/jp804086m

Abstract

We report on the preparation of ferromagnetic cobalt nanospheres with antiferromagnetic oxide capping layer and its implication for the variation in magnetic property. The hcp cobalt nanospheres were prepared by thermal decomposition of cobalt carbonyl in the presence of organic surfactants. The spherical nanoparticles thus prepared were oxidized to grow antiferromagnetic layers of varying composition and thickness on top of cobalt spheres. High-resolution transmission electron microscopy confirmed growth of Co3O4 in one case and CoO in another case. Strong exchange anisotropy and enhanced coercive field was observed due to the core−shell structure in the Co−CoO system. On the other hand only a marginal improvement was seen in the Co−Co3O4 system. A low-temperature paramagnetic behavior was also observed that is interpreted in the framework of crystal defects in the oxide shell.

Item Type:Article
Subjects:Physical Science > Nanophysics
Physical Science > Nano objects
Material Science > Nanochemistry
Material Science > Nanostructured materials
Divisions:Faculty of Engineering, Science and Mathematics > School of Physics
Faculty of Engineering, Science and Mathematics > School of Chemistry
ID Code:5045
Deposited By:JNCASR
Deposited On:27 May 2009 11:01
Last Modified:27 May 2009 11:01

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