sublattices ferrimagnet Cu2OSeO3 with a cubic symmetry and a linear
magnetoelectric effect. There is no spectroscopic evidence for
structural lattice distortions below T-C=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 T-C. 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. (c)
2010 American Institute of Physics. [doi:10.1063/1.3455808]