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Microstructure and Magnetic Properties of Co-CoO Nanocomposite Films

Published online by Cambridge University Press:  21 March 2011

Jae-Young Yi ,
G. A. Hirata  and
M. L. Rudee
Jae-Young Yi
Affiliation:
Material Science and Engineering, University of California, San Diego, La Jolla, CA 92093, U.S.A
G. A. Hirata
Affiliation:
CCMC-UNAM, Ensenada, B.C., 22860, Mexico
M. L. Rudee
Affiliation:
Material Science and Engineering, University of California, San Diego, La Jolla, CA 92093, U.S.A
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Abstract

The effect of exchange anisotropy on nanosize Co particles was studied in Co-CoO nanocomposite thin films for possible applications for magnetic storage media. XRD analyses showed nanosize hcp Co particles and (111) textured CoO phase. A broken columnar structure was observed in cross-section TEM images. Very large room temperature coercivity (∼1 kOe) was observed and believed to be due to a shape effect and possible local exchange coupling. Large exchange anisotropy at low temperatures and linear type temperature dependence were explained by finite size effects and thermal relaxation of the CoO particles. A slow decrease of thermoremanent moment (TRM) with temperature and large TRM at room temperature indicated that the exchange anisotropy significantly modified the anisotropy energy barrier of the Co crystallites in the CoO matrix. The results indicated that the exchange anisotropy could be used to stabilize nanosize ferromagnetic particles.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 674: Symposia T/U/V – Applications of Ferromagnetic and Optical Materials, Storage and Magnetoelectronics , 2001 , T3.4
Copyright
Copyright © Materials Research Society 2001

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