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Published August 23, 2001 | public
Journal Article

Crystalline, Shape, and Surface Anisotropy in Two Crystal Morphologies of Superparamagnetic Cobalt Nanoparticles by Ferromagnetic Resonance


Ferromagnetic resonance (FMR) techniques are used to investigate superparamagnetic cobalt nanoparticles (NP's) with different crystalline structures and sizes ranging from 4 to 9 nm in diameter. Magnetic contributions from NC shape, crystallographic structure, defects, and surface structure are discussed. An independent-superparamagnetic-grain model is employed to simulate the FMR measurements. The results from both single crystalline and polycrystalline cobalt NP's reveal that a particle's effective anisotropy, and thus its magnetic properties, are extremely sensitive to internal structure as well as overall particle shape. Finally, surface chemical properties were found to yield unique FMR signatures for NP's at low temperatures.

Additional Information

© 2001 American Chemical Society. Received 20 November 2000. Published online 20 July 2001. Published in print 1 August 2001. This work was supported through an NSF GOALI grant.

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