Exchange bias in GeMn nanocolumns: the role of surface oxidation
- Tardif, Samuel
- Cherifi, Salia
- Jamet, M.
- Devillers, T.
- Barski, A.
- Schmitz, D.
- Darowski, N.
- Thakur, P.
- Cezar, J. C.
- Brookes, N. B.
- Mattana, R.
- Cibert, Joel
DOIAbstract
International audienceWe 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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