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Hard Magnetic Nanoparticles and Nanocomposites

Published online by Cambridge University Press:  21 February 2011

Anit Giri,
Krishna Chowdary and
Sara A. Majetich
Anit Giri
Affiliation:
Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213
Krishna Chowdary
Affiliation:
Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213
Sara A. Majetich*
Affiliation:
Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213
*
Author to whom correspondence should be addressed. email: sm70@andrew.cmu.edu.
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Abstract

Many high performance permanent magnets are nanostructured materials. The magnetic properties of nanoparticles are discussed in terms of characteristic length scales, including the maximum monodomain size and the exchange length. Experimental results for ball milled SmCo5 nanoparticles are presented, showing deviations from idealized behavior. Because of the short exchange length, this can be understood in terms of independent nucleation of reverse domains in grains within larger particles. With a much longer exchange length, FeCo alloy nanoparticles show reduced coercivity in a high density compact, in accordance with the random anisotropy model. The SmCo5 and FeCo nanoparticles were mixed and compacted in an attempt to make an exchange spring nanocomposite. However, significant exchange between the hard and soft phases was not observed because the sample density was too low. Processing considerations for improved co-compaction of these nanoparticles are discussed.

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Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 577: Symposium H – Advanced Hard and Soft Magnetic Materials , 1999, 197
Copyright
Copyright © Materials Research Society 1999

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