Lattice dynamics of BaFe2Se3

M J Weseloh; V Balédent; W Zheng; M Verseils; P Roy; J B Brubach; D Colson; A Forget; P Foury-Leylekian; M-B Lepetit

doi:10.1088/1361-648X/ac640d

Lattice dynamics of BaFe₂Se₃

J Phys Condens Matter. 2022 May 6;34(25). doi: 10.1088/1361-648X/ac640d.

Authors

M J Weseloh^{1

2}, V Balédent³, W Zheng³, M Verseils⁴, P Roy⁴, J B Brubach⁴, D Colson⁵, A Forget⁵, P Foury-Leylekian³, M-B Lepetit^{1

2}

Affiliations

¹ Institut Néel, CNRS, Université Grenoble Alpes, 25 av. des Martyrs, 38042 Grenoble, France.
² Institut Laue-Langevin, 71 av. des Martyrs, 38000 Grenoble, France.
³ CNRS, Laboratoire de Physique des Solides, Université Paris-Saclay, 91405, Orsay, France.
⁴ Synchrotron SOLEIL, L'Orme des Merisiers, Saint Aubin BP 48, 91192, Gif-sur-Yvette, France.
⁵ SPEC, CEA, CNRS-UMR3680, Université Paris-Saclay, Gif-sur-Yvette Cedex 91191, France.

PMID: 35378521
DOI: 10.1088/1361-648X/ac640d

Abstract

This paper presents a study of the lattice dynamics in BaFe₂Se₃. We combined first-principle calculations, infrared measurements and a thorough symmetry analysis. Our study confirms thatPnmacannot be the space group of BaFe₂Se₃, even at room temperature. The phonons assignment requiresPmto be the BaFe₂Se₃space group, not only in the magnetic phase, but also in the paramagnetic phase at room temperature. This is due to a strong coupling between a short-range spin-order along the ladders, and the lattice degrees of freedom associated with the Fe-Fe bond length. This coupling induces a change in the bond-length pattern from an alternated trapezoidal one (as inPnma) to an alternated small/large rectangular one. Out of the two patterns, only the latter is fully compatible with the observed block-type magnetic structure. Finally, we propose a complete symmetry analysis of the BaFe₂Se₃phase diagram in the 0-600 K range.

Keywords: DFT; IR; multiferroics; phonons; symmetry.