A new polar symmetry of huebnerite (MnWO4) with ferrodistortive domains

Abstract Large-size single-crystal samples of huebnerite natural multiferroic MnWO 4 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 P 2 for the nuclear structure of huebnerite via the detection of weak reflections h 0 l ( 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 P 2 are displaced independently along the b axis from their equilibrium position at a polar point site, C 2 in P 2/ 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 P 2 domain formation through a proper ∼180° rotation about the reciprocal-space axis c *.