New insight on the phase diagram of the superconducting iron spin ladder BaFe$_2$S$_3$

Y. Oubaid; V. Balédent; O. Fabelo; C. V. Colin; S. Chattopadhyay; E. Elkaim; A. Forget; D. Colson; D. Bounoua; M. Verseils; P. Fertey; P. Foury-Leylekian

arXiv · 2503.10942

New insight on the phase diagram of the superconducting iron spin ladder BaFe$_2$S$_3$

Y. Oubaid·V. Balédent·O. Fabelo·C. V. Colin·S. Chattopadhyay·E. Elkaim·A. Forget·D. Colson·D. Bounoua·M. Verseils·P. Fertey·P. Foury-Leylekian

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Abstract

BaFe$_2$S$_3$ and BaFe$_2$Se$_3$ are the only two quasi-one-dimensional iron-based compounds that become superconductors under pressure. Interestingly, these two compounds exhibit different symmetries and properties. While more detailed and recent studies on BaFe$_2$Se$_3$ using single crystals have advanced the filed towards a more universal description of this family, such a study is still lacking for the compound BaFe$_2$S$_3$. Here, we present a detailed study of the crystalline and magnetic structure performed on single crystals using X-ray and neutron diffraction. We demonstrate a polar structure at room temperature within the $Cm2m$ space group, followed by a structural transition at 130 K to the polar $Pb2_1m$ space group. This space group remains unchanged across the magnetic transition at $T_N =95$ K, revealing multiferroic characteristics with a weak magnetoelastic coupling. The determined magnetic structure is monoclinic ($P_am$), with non-collinear magnetic moments, displaying a significant angle of 18$^\circ$ relative to the $a$-axis in the $(a, c)$ plane. This reexamination of the temperature-dependent properties of BaFe$_2$S$_3$ provides new insights into the physics of this system from multiple key perspectives.

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Y. Oubaid, V. Balédent, O. Fabelo, C. V. Colin, S. Chattopadhyay, E. Elkaim, A. Forget, D. Colson, D. Bounoua, M. Verseils, P. Fertey, P. Foury-Leylekian. 2025-03-13. New insight on the phase diagram of the superconducting iron spin ladder BaFe$_2$S$_3$. https://arxiv.org/abs/2503.10942

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