Regensburg 2010 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 41: Poster Session I (Semiconductor Substrates: Epitaxy and growth; Semiconductor Substrates: Adsorbtion; Semiconductor Substrates: Solid-liquid interfaces; Semiconductor Substrates: Clean surfaces; Oxides and insulators: Epitaxy and growth; Oxides and insulators: Adsorption; Oxides and insulators: Clean surfaces; Organic, polymeric and biomolecular films - also with adsorbates; Organic electronics and photovoltaics, Surface chemical reactions; Heterogeneous catalysis; Phase transitions; Particles and clusters; Surface dynamics; Surface or interface magnetism; Electron and spin dynamics; Spin-Orbit Interaction at Surfaces; Electronic structure; Nanotribology; Solid/liquid interfaces; Graphene; Others)

O 41.74: Poster

Dienstag, 23. März 2010, 18:30–21:00, Poster B1

XMCD of ultrathin magnetite (Fe₃O₄) films on titanates (BaTiO₃, SrTiO₃) — Remya Govind¹, •Martin Trautmann¹, Franziska Steudel¹, Michael Huth¹, Stephan Borek¹, Liudmilla Makhova², Joachim Gräfe², Daniel Wett², Vasili Hari Babu², Angelika Chassé¹, Karl-Michael Schindler¹, and Reinhard Denecke² — ¹Institute of Physics, Martin-Luther-University Halle-Wittenberg, Germany — ²Wilhelm-Ostwald-Institute for Physical and Theoretical Chemistry, University Leipzig, Germany

Coupling ferromagnetism to ferroelectricity in multiferroic systems raises interesting fundamental and application related questions. Within the framework of the SFB 762 all-oxide systems (magnetite on titanates) have been investigated using x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) at BESSY II. Thin and ultrathin films of magnetite (Fe₃O₄) have been prepared by reactive metal evaporation of iron in an O₂ atmosphere and characterized using XAS. The controversy about published assignments of XAS spectra to SrTiO₃ and BaTiO₃ could be resolved on the basis of experimental O K-edge and Ti L-edge spectra and multiple scattering calculations. After in-plane magnetization the XMCD of the films has been determined in grazing incidence at room temperature. Thin films of Fe₃O₄ (30 ML on SrTiO₃ and 10 ML on BaTiO₃) exhibited an XMCD comparable to published data of bulk and bulk-like systems. However, an ultrathin film on BaTiO₃ with a thickness of 3 ML showed no XMCD. Obviously, remanent in-plane magnetization could no longer be achieved.