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|Title:||Exchange bias in UO2/Fe3O4 thin films above the Néel temperature of UO2|
|Authors:||TERESHINA Evgenia; BAO ZHAOHUI; HAVELA L.; DANIS S.; KUEBEL Christian; GOUDER Thomas; CACIUFFO Roberto|
|Citation:||APPLIED PHYSICS LETTERS vol. 105 no. 12 p. 122405|
|Publisher:||AMER INST PHYSICS|
|Type:||Articles in periodicals and books|
|Abstract:||Magnetic exchange bias (EB) has been investigated on antiferromagnetic/ferrimagnetic heterostructures consisting of a stoichiometric UO2 film grown epitaxially on a LaAlO3 substrate and covered with highly textured Fe3O4 layers of variable thickness (t Fe3O4 = 90–700 Å). EB values reaching ∼2.6 kOe were observed at lowest temperatures in UO2/Fe3O4 with the thinnest Fe3O4. Magnetization measurements demonstrate that a remarkably large exchange bias in UO2/Fe3O4 is present at temperatures higher than the bulk N é el temperature of UO2 (T N = 30.8 K). Our study reveals a complex nature of the effect: we suggest that it is provided both by strong exchange coupling between UO2 and Fe3O4 and by exchange biasing within magnetite (up to 25% of the total effect at 5 K in the UO2/Fe3O4 sample with the largest EB). The former can be caused by proximity effects of Fe3O4 on T N combined with a magnetic anisotropy of UO2, persisting above a continuous magnetic-ordering transformation. For magnetite, the results indicate the presence of pinned moments up to 120 K that correlates with the change in the easy magnetization axis of Fe3O4 across the Verwey transition.|
|JRC Directorate:||Nuclear Safety and Security|
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