Lattice dynamics ofBaFe2X3(X=S,Se)compounds

Abstract

We present the Raman scattering spectra of the BaFe2X3 (X=S, Se) compounds in a temperature range between 20 K and 400 K. Although the crystal structures of these two compounds are both orthorhombic and very similar, they are not isostructural. The unit cell of BaFe2S3 (BaFe2Se3) is base-centered Cmcm (primitive P nma) giving totaly 18 (36) modes to be observed in the Raman scattering experiment. We have detected almost all Raman active modes, predicted by factor group analysis, which can be observed from the cleavage planes of these compounds. Assignment of the observed Raman modes of BaFe2S(Se)3 is supported by the lattice dynamics calculations. The antiferromagnetic long-range spin ordering in BaFe2Se3 below TN =255 K leaves a fingerprint both in the A1g and B3g phonon mode linewidth and energy.

Temperature‐Dependent Raman Study of Nanostructured and Multifunctional Materials

“…The BaFe 2 S 3 is a quasi‐one‐dimensional semiconductor with orthorhombic crystal symmetry, with space group Cmcm and Z = 4. Based on the factor group analysis, the 18 Raman active modes are expected to be registered in the spectra of single‐crystal with (110) orientation . Most of these modes are observed in polarized Raman scattering spectra of BaFe 2 S 3 investigated here (Figure a).…”

“…The crystal structures of the BaFe 2 S 3 and BaFe 2 Se 3 , representatives of the iron‐based S = 2 two‐leg spin‐ladder compound family, are isomorphic, but not isostructural . They can be described as alternate stacking of Fe‐S(Se) layers and Ba cations along the crystallographic a axis ( b axis), whereas in the Fe‐S(Se) plane, only one‐dimensional (1D) double chains of edge‐shared [FeS(Se)] 4 tetrahedra propagate along these axes.…”

“…Experimental values (symbols) and calculated temperature dependence (solid lines) of the energies and broadenings of (b) and (c) Raman modes of BaFe 2 S 3 , with the normal modes of corresponding vibrations graphically represented in the insets. Reproduced with permission . Copyright 2015, American Physical Society.…”

“…These materials may have not only superconducting but also low‐dimensional magnetic properties (forming spin chains, spin ladders, spin dimers, etc.) . The temperature dependent Raman spectra of iron‐based sulphides and selenides (BaFe 2 S 3 and BaFe 2 Se 3 , belonging to the family of the iron‐based S = 2 two‐leg spin‐ladder compounds), together with alkali‐doped iron selenides (superconducting K x Fe 2− y Se 2 and non‐superconducting K 0.8 Fe 1.8 Co 0.2 Se 2 ) are analyzed.…”

“…. The temperature dependent Raman spectra of iron‐based sulphides and selenides (BaFe 2 S 3 and BaFe 2 Se 3 , belonging to the family of the iron‐based S = 2 two‐leg spin‐ladder compounds), together with alkali‐doped iron selenides (superconducting K x Fe 2− y Se 2 and non‐superconducting K 0.8 Fe 1.8 Co 0.2 Se 2 ) are analyzed. A physical model, including thermal expansion, as well as three‐ and four‐phonon anharmonic effects, is used to quantitatively analyze experimentally obtained temperature dependence of energy and linewidth of the Raman modes characteristic for investigated materials.…”