Berlin 2008 – scientific programme

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MA: Fachverband Magnetismus

MA 28: Magnetic Thin Films III

MA 28.4: Talk

Thursday, February 28, 2008, 15:15–15:30, H 1012

Iron and its native oxide: From chemical structure to magnetic ordering — •Sebastien Couet¹, Kai Schlage¹, Karel Saksl², and Ralf Röhslberger¹ — ¹Hamburger Synchrotron Strahlungslabor (HASYLAB) at Deutsches Elektronen-Synchrotron (DESY), Notkestr. 85, 22607 Hamburg — ²IMR, Slovak Academy of Sciences Watsonova, 4704353 Kosice, Slovak republic

It has been demonstrated recently that a strong non collinear magnetic coupling appears between metallic iron layers separated by nanolayer of native iron oxide[1]. Although the microscopic coupling mechanism is not fully understood, theoretical models suggest that it is due to an antiferromagnetic (AFM) order of the oxide layer. As the different oxide phases of iron appear in different magnetic states, it is crucial to resolve the chemical structure of the native oxide to understand the underlying magnetic properties. We therefore investigated the oxidation process in-situ by X-ray absorption spectroscopy. This technique allows us to get quantitative information about the chemistry and the local order in the layer. The study shows that the native oxide at saturation is composed of a mixture of iron oxide phases with a predominance of Fe³⁺ iron species. Upon coverage by a thin iron layer, the oxide is completely reduced and only an FeO like phase remains. This quantitative study shows that it is possible to control the thickness and structure of those native oxide and open the possibility to tailor the magnetic coupling of the system.

[1] Th. Diederich, S. Couet, R. Röhlsberger, Phys. Rev. B 76, 54401 (2007).