Origin of forbidden reflections in multiferroic Ba2CoGe2O7 by neutron diffraction: symmetry lowering or Renninger effect?

Sazonov, A. and Meven, M. and Roth, G. and Georgii, R. and Kézsmárki, István and Kocsis, Vilmos (2016) Origin of forbidden reflections in multiferroic Ba2CoGe2O7 by neutron diffraction: symmetry lowering or Renninger effect? JOURNAL OF APPLIED CRYSTALLOGRAPHY, 49. pp. 556-560. ISSN 0021-8898

Preview

Text 1511.02783.pdf Available under License Creative Commons Attribution. Download (467kB) | Preview

Abstract

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, Nafradi & 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 (4) over bar2(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.

Actions (login required)

Edit Item