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Updated: Jul 31, 2026

Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses
Published on: June 7, 2018
Difference between blocking and Néel temperatures in the exchange biased Fe3O4/CoO system
P J van der Zaag1, Y Ijiri, J A Borchers
1Philips Research Laboratories and CFT, Prof. Holstlaan 4, 5656 AA Eindhoven, The Netherlands. P.J.van.der.Zaag@philips.com
Abstract:
The blocking temperature T(B) has been determined as a function of the antiferromagnetic layer thickness in the Fe3O4/CoO exchange biased system. For CoO layers thinner than 50 A, T(B) is reduced below the Néel temperature T(N) of bulk CoO (291 K), independent of crystallographic orientation or film substrate ( alpha-Al2O3, SrTiO3, and MgO). Neutron diffraction studies show that T(B) does not track the CoO ordering temperature and, hence, that this reduction in T(B) does not arise from finite-size scaling. Instead, the ordering temperature of the CoO layers is enhanced above the bulk T(N) for layer thicknesses approximately less than or equal to 100 A due to the proximity of magnetic Fe3O4 layers.
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