Berlin 2012 – scientific programme

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MA: Fachverband Magnetismus

MA 8: Magnetic Particles / Clusters I

MA 8.3: Talk

Monday, March 26, 2012, 18:15–18:30, EB 202

Site specific spin canting in Fe oxide nanoparticles — •Anne Warland¹, Carolin Antoniak¹, Masih Darbandi¹, Detlef Schmitz², Tobias Euwens¹, and Heiko Wende¹ — ¹Fakultät für Physik und CeNIDE — ²Helmholtz-Zentrum Berlin für Materialien und Energie

It is well known that Fe oxide nanoparticles can hardly be saturated due to spin canting at the surface. From our Mössbauer spectroscopy measurements we obtained indications that the canting takes place mainly at the Fe sites which are octahedrally surrounded by the oxygen. Contrary, the Fe spins at tetrahedral sites are only slightly canted. Explanations for this canting effect are vacancies and missing bonds at the particles surface. XMCD spectroscopy at the Fe L_3,2 absorption edges allows to separate the magnetic contributions of Fe²⁺ and Fe³⁺ ions at tetrahedral and octahedral sites. We used this technique to determine the field dependent magnetization and to monitor the spin canting site specifically. Bare iron oxide nanoparticles of different sizes (3nm, 6nm and 9nm) have been investigated in magnetic fields up to 5T. This work is supported by DFG(WE2623/3-1)