| Original Articles |
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New Features of the Coercivity in Exchange-Coupled Ni81Fe19/CoO Bilayers |
| CAI Jian-Wang，LAI Wu-Yan |
| State Key Laboratory of Magnetism, Institute of Physics and
Center for Condensed Matter Physics, Chinese Academy of Sciences, Beijing 100080
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| Cite this article: |
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CAI Jian-Wang, LAI Wu-Yan 2001 Chin. Phys. Lett. 18 1651-1654 |
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Abstract The coercivity behaviour of the Ni81Fe19 film exchange-coupled with an antiferromagnetic CoO underlayer has been investigated systematically. It has been found that the coercivity is greatly enhanced not only at the easy axis but also at the hard axis direction when the temperature is below the Néel temperature of CoO, Also, the thickness dependence of coercivity at low temperature follows the scaling relation as 1/tαNiFe with α = 2.5 at the hard axis, which is quite in contrast with the case of the easy axis, i.e., α =1.5, predicted theoretically and verified experimentally previously. The increase of the temperature leads to the decrease of the coercivity at both the easy and hard axes, but the scaling relations are held except the narrow region just below the Néeel temperature of CoO, at which the coercivity varies as 1/tαNiFe with α = 1.0 for both the easy and hard axes. Based upon Hoffmann's ripple theory and Malozemoff's random field model, a simple interpretation on the experiment findings is presented.
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| Keywords:
75.70.Cn
75.30.Gw
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Published: 01 December 2001
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| PACS: |
75.70.Cn
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(Magnetic properties of interfaces (multilayers, superlattices, heterostructures))
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75.30.Gw
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(Magnetic anisotropy)
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