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Interfaceless Exchange Bias in CoFe₂O₄ Nanocrystals.

ABSTRACT: Oxidized cobalt ferrite nanocrystals with a modified distribution of the magnetic cations in their spinel structure give place to an unusual exchange-coupled system with a double reversal of the magnetization, exchange bias, and increased coercivity, but without the presence of a clear physical interface that delimits two well-differentiated magnetic phases. More specifically, the partial oxidation of cobalt cations and the formation of Fe vacancies at the surface region entail the formation of a cobalt-rich mixed ferrite spinel, which is strongly pinned by the ferrimagnetic background from the cobalt ferrite lattice. This particular configuration of exchange-biased magnetic behavior, involving two different magnetic phases but without the occurrence of a crystallographically coherent interface, revolutionizes the established concept of exchange bias phenomenology.

SUBMITTER: Rivas-Murias B

PROVIDER: S-EPMC10848284 | biostudies-literature | 2023 Mar

REPOSITORIES: biostudies-literature

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Interfaceless Exchange Bias in CoFe2O4 Nanocrystals.

Rivas-Murias Beatriz B Testa-Anta Martín M Skorikov Alexander S AS Comesaña-Hermo Miguel M Bals Sara S Salgueiriño Verónica V

Nano letters 20230227 5

Oxidized cobalt ferrite nanocrystals with a modified distribution of the magnetic cations in their spinel structure give place to an unusual exchange-coupled system with a double reversal of the magnetization, exchange bias, and increased coercivity, but without the presence of a clear physical interface that delimits two well-differentiated magnetic phases. More specifically, the partial oxidation of cobalt cations and the formation of Fe vacancies at the surface region entail the formation of ...[more]

PMID: 36848327

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