Regensburg 2010 – wissenschaftliches Programm

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DF: Fachverband Dielektrische Festkörper

DF 5: Multiferroics II (Joint Session of MA, DF, KR, DS)

DF 5.9: Vortrag

Montag, 22. März 2010, 16:15–16:30, H3

Multiferroicity in EuTiO₃ and Eu_1−xBa_xTiO₃: ab initio characterization of crystalline, magnetic and electronic structure — •Konstantin Z. Rushchanskii¹, Marjana Ležaić¹, and Nicola A. Spaldin² — ¹Institut für Festkörperforschung, Quanten-Theorie der Materialien, Forschungszentrum Jülich GmbH, 52425 Jülich, and JARA-FIT, Germany — ²Materials Department, University of California, Santa Barbara, CA 93106-5050, USA

We report a systematic study of possible structural transitions in EuTiO₃ and ordered Eu_1−xBa_xTiO₃ mixed compounds. We investigated phonon spectra of EuTiO₃ and found strong M- and R-point instabilities, indicating antiferrodistortive structural deformations. In the ordered Eu_0.5Ba_0.5TiO₃ compounds, the antiferrodistortive deformation is replaced by significant ferroelectric distortions, involving not only Ti, but also the magnetic Eu cation. We will discuss several scenarios of ferroelectric and antiferrodistortive transitions and their coupling with the magnetic structure. Corresponding changes in the phonon structure will be compared with available experimental data.