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Magnetic Hardening Induced by Exchange Coupling in Mechanically Milled Antiferromagnetic - Ferromagnetic Composites

Published online by Cambridge University Press:  21 February 2011

J. Sort ,
J. Nogués ,
X. Amils ,
S. Suriñach ,
J.S. Muñoz  and
M.D. Baró
J. Sort
Affiliation:
Departament de Física, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
J. Nogués
Affiliation:
Departament de Física, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
X. Amils
Affiliation:
Departament de Física, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
S. Suriñach
Affiliation:
Departament de Física, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
J.S. Muñoz
Affiliation:
Departament de Física, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
M.D. Baró
Affiliation:
Departament de Física, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
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Abstract

Mechanical milling has been used to synthesize ferromagnetic (FM, Co) - antiferromagnetic (AFM, NiO) composites. The coercivity, HC, and energy product, BHMax, of these composites can be enhanced at room temperature after appropriate heat treatments above the Néel temperature of the AFM, TN. Although the maximum Hc is achieved for the (NiO)1: 1 (Co) weight ratio, BHMax is further enhanced for the (NiO)2:3(Co) ratio, where higher saturation magnetization is obtained due to the larger amount of FM. Exchange coupling, responsible for these effects, decreases as the temperature is increased and vanishes close to TN. The thermal stability of the coercivity enhancement remains rather insensitive to the somewhat broad distribution of blocking temperatures of this system.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 581: Symposium F – Nanophase & Nanocomposite Materials II , 1999 , 641
Copyright
Copyright © Materials Research Society 2000

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References

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