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arXiv · 1008.2872

Exchange bias in GeMn nanocolumns: the role of surface oxidation

S. Tardif·S. Cherifi·M. Jamet·T. Devillers·A. Barski·D. Schmitz·N. Darowski·P. Thakur·J. C. Cezar·N. B. Brookes·R. Mattana·J. Cibert
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Abstract

We report on the exchange biasing of self-assembled ferromagnetic GeMn nanocolumns by GeMn-oxide caps. The x-ray absorption spectroscopy analysis of this surface oxide shows a multiplet fine structure that is typical of the Mn2+ valence state in MnO. A magnetization hysteresis shift |HE|~100 Oe and a coercivity enhancement of about 70 Oe have been obtained upon cooling (300-5 K) in a magnetic field as low as 0.25 T. This exchange bias is attributed to the interface coupling between the ferromagnetic nanocolumns and the antiferromagnetic MnO-like caps. The effect enhancement is achieved by depositing a MnO layer on the GeMn nanocolumns.

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S. Tardif, S. Cherifi, M. Jamet, T. Devillers, A. Barski, D. Schmitz, N. Darowski, P. Thakur, J. C. Cezar, N. B. Brookes, R. Mattana, J. Cibert. 2010-08-17. Exchange bias in GeMn nanocolumns: the role of surface oxidation. https://doi.org/10.1063/1.3476343

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