Article ID Journal Published Year Pages File Type
1798977 Journal of Magnetism and Magnetic Materials 2015 13 Pages PDF
Abstract

•Neutron and X-ray diffraction analyzes reveal the polar symmetry P2 for MnWO4.•Raman mapping shows ferrodistortive domains in its RT paramagnetic state.•These observations are explained by the hidden polar site C2 for Mn atoms.

Large-size single-crystal samples of huebnerite natural multiferroic MnWO4 were analyzed by neutron and synchrotron X-ray single-crystal diffraction as well as by polarized Raman spectroscopy. Both neutron and X-ray diffraction analyzes reveal polar space-group symmetry P2 for the nuclear structure of huebnerite via the detection of weak reflections h0l (l=odd) forbidden for the gliding plane c. Renninger scans of the reflection 301 on the neutron single-crystal diffractometer RESI (FRM-II) could confirm the absence of the gliding plane c in both para- and antiferromagnetic states of huebnerite. The symmetry breaking could be explained by structure analyzes with neutron single crystal diffraction data at 293 K revealing that two Mn atoms in P2 are displaced independently along the b axis from their equilibrium position at a polar point site, C2 in P2/c. Micro X-ray diffraction and Raman-scattering mapping reveal a ferrodistortive domain texture in the room-temperature paramagnetic state of huebnerite, which is attributed to P2 domain formation through a proper ∼180° rotation about the reciprocal-space axis c*.

Graphical abstractSchematic presentation of polar atomic shifts (arrows) in P2 from the respective equivalent sites (spheres) in P2/c at the boundary of two 180°-in-plane micro twins.Figure optionsDownload full-size imageDownload as PowerPoint slide

Related Topics
Physical Sciences and Engineering Physics and Astronomy Condensed Matter Physics
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