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Tuning the ferromagnetic-antiferromagnetic interfaces of granular Co-CoO exchange bias systems by annealing

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Tuning the ferromagnetic-antiferromagnetic interfaces of granular Co-CoO exchange bias systems by annealing

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Título Tuning the ferromagnetic-antiferromagnetic interfaces of granular Co-CoO exchange bias systems by annealing
Autor Menéndez Dalmau, Enric
Modarresi, Hiwa
Dias, Thiago
Geshev, Julian Penkov
Pereira, Lino Miguel da Costa
Temst, Kristiaan
Vantomme, A.
Abstract The low-temperature magnetic behavior of granular Co-CoO exchange bias systems, prepared by oxygen ion implantation in Co thin films and subsequent annealing, is addressed. The thermal activation effects lead to an O migration which results in virtually pure Co areas embedded in a structurally relaxed and nearly stoichiometric CoO phase. This yields decreased training and exchange bias shifts, while the blocking temperature significantly increases, coming close to the N'eel temperature of bulk CoO for samples implanted to a fluence above 1 x 1017 ions/cm² (15% O). The dependence of the exchange bias shift on the pristine O-implanted content is analogous to that of the antiferromagnetic thickness in most ferromagnetic/antiferromagnetic systems (i.e., an increase in the exchange bias shift up to a maximum followed by a decrease until a steady state is reached), suggesting that, after annealing, the enriched Co areas might be rather similar in size for samples implanted above 1 x 1017 ions/cm², whereas the corresponding CoO counterparts become enlarged with pristine O content (i.e., effect of the antiferromagnet size). This study demonstrates that the magnetic properties of granular Co-CoO systems can be tailored by controllably modifying the local microstructure through annealing treatments.
Contido em Journal of applied physics. New York. Vol. 115, no. 13 (Apr. 2014), 133915, 5 p.
Assunto Compostos de cobalto
Estequiometria
Filmes finos magneticos
Filmes finos metalicos
Implantacao ionica
Materiais antiferromagnéticos
Materiais ferromagneticos
Materiais granulares
Microestrutura cristalina
Particulas magneticas
Temperatura de Neel
Origem Estrangeiro
Tipo Artigo de periódico
URI http://hdl.handle.net/10183/107864
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