Regensburg 2010 – wissenschaftliches Programm

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KR: Fachverband Kristallographie

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

KR 10.13: Poster

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

Properties of TiO₂/Fe composites investigated by ab inito calculations — •Anna Grünebohm, Heike C. Herper, and Peter Entel — Fakultät für Physik, Universität Duisburg-Essen

Multiferroic materials offer interesting new applications through the coupling or coexistence of two order parameters - particularly ferroelectricity and ferromagnetism. While ferromagnetism is mainly mediated by highly localized d- and f- electrons, conventional ferroelectricity is mediated by cation off-centering which is based on empty d-shells. Therefore, multicomponent systems are promising alternatives for high performance multiferroics [1]. In such composites, the ferroelectric and ferromagnetic phases are coupled through hybridization and strain effects at the interfaces. To get an insight into the interface properties of such systems, we do calculations within the projector augmented wave method using VASP [2]. We investigate Fe/TiO₂ agglomerates as simple model systems in order to study fundamental properties of such interfaces. Although TiO₂ does not possess a ferroelectric phase, it offers a large polarizability and a magnetoelectric effect has been measured in Fe/TiO_2−δ films [3]. This means that TiO₂ interfaces possess similar properties as ferroelectrics. Until now little is konwn of the interface structure of TiO₂/Fe agglomerates. Hence, we present a systematic study of different layered systems as well as agglomerated nanoparticles.

[1] R. Ramesh and N. A. Spaldin, Nat. Mater. 6, 21 (2007) [2] G. Kresse and J. Furthmüller, Phys. Rev. B 54, 11169 (1996) [3] S. D. Yoon, et al, Appl. Phys. Lett. 92, 042508 (2008)