TY  - JOUR
AU  - Sazonov, Andrew
AU  - Meven, Martin
AU  - Roth, Georg
AU  - Georgii, Robert
AU  - Kézsmárki, István
AU  - Kocsis, Vilmos
AU  - Tokunaga, Yusuke
AU  - Taguchi, Yasujiro
AU  - Tokura, Yoshinori
AU  - Hutanu, Vladimir
TI  - Origin of forbidden reflections in multiferroic Ba$_{2}$CoGe$_{2}$O$_{7}$ by neutron diffraction: symmetry lowering or Renninger effect?
JO  - Journal of applied crystallography
VL  - 49
IS  - 2
SN  - 1600-5767
CY  - Copenhagen
PB  - Munksgaard
M1  - FZJ-2016-07019
SP  - 556 - 560
PY  - 2016
AB  - For a symmetry-consistent theoretical description of the multiferroic phase of Ba2CoGe2O7 a precise knowledge of its crystal structure is a prerequisite. In a previous synchrotron X-ray diffraction experiment on multiferroic Ba2CoGe2O7 at room temperature, forbidden reflections were found that favour the tetragonal-to-orthorhombic symmetry lowering of the compound [Hutanu, Sazonov, Murakawa, Tokura, Náfrádi & Chernyshov (2011), Phys. Rev. B, 84, 212101]. Here, the results are reported of room-temperature single-crystal diffraction studies with both hot and cold neutrons to differentiate between genuine symmetry lowering and multiple diffraction (the Renninger effect). A comparison of the experimental multiple diffraction patterns with simulated ones rules out symmetry lowering. Thus, the structural model based on the tetragonal space group P\overline{4}2_{1}m was selected to describe the Ba2CoGe2O7 symmetry at room temperature. The precise structural parameters from neutron diffraction at 300 K are presented and compared with the previous X-ray diffraction results.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000373702000025
DO  - DOI:10.1107/S1600576716002405
UR  - https://juser.fz-juelich.de/record/824430
ER  -