Regensburg 2010 – wissenschaftliches Programm

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KR: Fachverband Kristallographie

KR 10: Poster: Multiferroics (with MA, DF, KR, DS)

KR 10.75: Poster

Dienstag, 23. März 2010, 10:45–13:45, Poster A

X-Ray magnetic circular dichroism (XMCD) study of magnetite (Fe₃O₄) thin films on semiconducting substrates — •Dominik Kufer, Markus Paul, Andreas Müller, Christian Praetorius, Annemarie Köhl, Kai Fauth, Michael Sing, and Ralph Claessen — Lehrstuhl für Experimentelle Physik 4, Universität Würzburg, Germany

Thin films of magnetite have attracted enormous research interest in recent years because of their electronic and magnetic properties. Bulk magnetite shows ferrimagnetic ordering with a theoretically predicted magnetic moment of 4µ_B per formula unit below a favorably high Curie temperature of 850 K. However, structural, electronic and magnetic properties of thin films depend on choice of substrate, deposition method, and various process parameters. We have investigated the magnetic properties of epitaxial Fe₃O₄ thin films on the technologically relevant semiconducting substrates ZnO and GaAs by means of XMCD. Thin films were deposited by oxygen-assisted MBE and characterized by LEED, XPS and XRD. XMCD measurements were performed on samples with film thicknesses ranging from 3 to 40 nm, grown both ex situ as well as in situ shortly before data acquisition in total electron yield (TEY) mode. Our XMCD results confirm rather reduced magnetic moments in comparison with Fe₃O₄ bulk values [1]. Sum rule evaluation leads to spin magnetic moments in the range of 0.7-1.0µ_B per atom and nearly vanishing orbital moments for both substrates.

[1] A.Müller et al., arXiv:0911.3572