Magnetic anisotropy of Co2+ as signature of intrinsic ferromagnetism in ZnO:Co.
We report on the magnetic properties of thoroughly characterized Zn(1-x)Co(x)O epitaxial thin films, with low Co concentration, x = 0.003-0.005. Magnetic and EPR measurements, combined with crystal field theory, reveal that isolated Co2+ ions in ZnO possess a strong single ion anisotropy which leads to an "easy plane" ferromagnetic state when the ferromagnetic Co-Co interaction is considered. We suggest that the peculiarities of the magnetization process of this state can be viewed as a signature of intrinsic ferromagnetism in ZnO:Co materials.
Laboratoire Matériaux et Microélectronique de Provence, Case-142, Université d'Aix-Marseille III and CNRS, 13397, Marseille Cedex 20, France.
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Sati
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Hayn
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Kuzian
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Régnier
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S
Schäfer
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A
Stepanov
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Morhain
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Deparis
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Laügt
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Goiran
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Golacki