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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 (T_N ∼ 370 ^∘C) and ferroelectric (T_C ∼ 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.