Regensburg 2007 – scientific programme

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MA: Fachverband Magnetismus

MA 27: Micro- and Nanostructured Magnetic Materials II

MA 27.6: Talk

Thursday, March 29, 2007, 16:30–16:45, H22

Domain structure of epitaxial magnetite films with weak magnetic coupling — •Ivo Knittel¹, Ulrike Wolff², Volker Neu², Louise McGuigan³, Yang Zhou³, Sunil Arora³, Igor Shvets³, and Uwe Hartmann¹ — ¹Fachbereich Experimentalphysik, Im Stadtwald, Geb. C6.3, 66041 Saarbrücken — ²IFW Dresden, P.O. Box: 270116, 01171 Dresden — ³CRANN, Trinity College Dublin, College Green, Dublin 2, Ireland

In epitaxial magnetite films, an unsual domain structure is produced by slight post-oxidation. The resulting domain pattern could be explained by application of the theory of weak stripe domains, presupposing a perpendicular anisotropy. The strong local magnetization disorder and dipolar magnetization reversal events have been related to antiferromagnetic coupling across antiphase boundaries (APB). We report on magnetic force microscopy imaging over the full magnetization curve, and measurements of the magnetic anisotropy by ferromagnetic resonance. Results are best described not by antiferromagnetic coupling, but by a weakened exchange across APB. Our epitaxial magnetite film with APB can therefore be regarded as a partly exchange-isolated nanocrystalline material.