Berlin 2008 – wissenschaftliches Programm
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DF: Fachverband Dielektrische Festkörper
DF 3: Phase Transitions
DF 3.4: Vortrag
Montag, 25. Februar 2008, 11:40–12:00, EB 407
Pressure-induced phase transitions in the multiferroic BiFeO3 studied by infrared spectroscopy — •Alexej Pashkin1, Kaneez Rabia1, Simone Frank1, Raphael Haumont2, Jens Kreisel3, and Christine A. Kuntscher1 — 1Experimentalphysik II, Universität Augsburg, , 86159 Augsburg, Germany — 2Laboratoire de Physico-Chimie de l’Etat Solide ICMMO - UMR CNRS, Université Paris Sud, 91405 Orsay Cedex, France — 3Laboratoire des Matériaux et du Génie Physique (CNRS), INP Grenoble - MINATEC 38016 Grenoble, France
BiFeO3 is considered to be one of the model multiferroic materials with unusually high temperatures of antiferromagnetic (TN ∼ 370 ∘C) and ferroelectric (TC ∼ 830 ∘C) ordering. Recently, an extremely high spontaneous polarization has been reported for BiFeO3 thin films, ceramics and crystals making this material very attractive for applications. BiFeO3 presents a complex interplay between the magnetic, ferroelectric and ferroelastic order parameters. Thus, a particularly rich phase diagram is expected for this material.
We report a high-pressure infrared spectroscopic study of high-quality BiFeO3 single crystals in the far-infrared range up to 10 GPa. The observed behavior of the infrared phonon modes under pressure clearly reveals two structural phase transitions around 3.0 and 7.5 GPa supporting the results of recent Raman and x-ray diffraction studies under pressure. Financially supported by the DFG (Emmy Noether-program, SFB 484). Provision of beamtime at the ANKA (Karlsruhe) is acknowledged.