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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.