Low Temperature Physics: 36, 550 (2010); https://doi.org/10.1063/1.3455808 (8 pages)
Физика Низких Температур: Том 36, Выпуск 6 (Июнь 2010), c. 688-697    ( к оглавлению , назад )

Magnetoelectricity in the ferrimagnetic Cu2OSeO3:symmetry analysis and Raman scattering study

V.P. Gnezdilov1, K.V. Lamonova2, Yu.G. Pashkevich2, P. Lemmens3, H. Berger4, F. Bussy5, and S.L. Gnatchenko1

1B.I. Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine 47 Lenin Ave., Kharkov 61103, Ukraine
E-mail: gnezdilov@ilt.kharkov.ua

2A.A. Galkin Donetsk Phystech of the National Academy of Sciences of Ukraine, Donetsk 83114, Ukraine

3Institute for Condensed Matter Physics, TU Braunschweig, D-38106 Braunschweig, Germany

4Institute of Condensed Matter Physics, Ecole Polytechnique Fédérale de Lausanne, CH-1015, Lausanne, Switzerland

5Institute of Mineralogy and Geochemistry, ANTHROPOLE, University of Lausanne, CH-1015 Lausanne, Switzerland

Received March 10, 2010

Аннотация

We report Raman scattering studies and magneto/structural symmetry analysis of the many sublattices ferrimagnet Cu2OSeO3 with a cubic symmetry and a linear magnetoelectric effect. There is no spectroscopic evidence for structural lattice distortions below TC = 60 K, which are expected due to magnetoelectric coupling. Using symmetry arguments we explain this observation by considering a special type of ferrimagnetic ground state which does not generate a spontaneous electric polarization. Interestingly, Raman scattering shows a strong increase of electric polarization of media through a dynamic magnetoelectric effect as a remarkable enhancement of the scattering intensity below TC. New lines of purely magnetic origin have been detected in the magnetically ordered state. A part of them are attributed as scattering on exchange magnons. Using this observation and further symmetry considerations we argue for strong Dzyaloshinskii–Moriya interaction existing in the Cu2OSeO3.

PACS: 78.30.–j Infrared and Raman spectra;
PACS: 75.50.Gg Ferrimagnetics;
PACS: 77.84.Bw Elements, oxides, nitrides, borides, carbides, chalcogenides, etc.;
PACS: 63.20.–e Phonons in crystal lattices.

Ключевые слова: ferrimagnetism, magnetoelectric effect, symmetry analysis, Raman scattering, phonons, magnon modes.