Coexistence of superconductivity and magnetic order in BaFe$_2$S$_3$: evidence for orbital-selective delocalization

Y. Oubaid; N. S. Dhami; P. Fertey; C. V. Colin; C. Ritter; A. Forget; D. Bounoua; J. -P. Rueff; M. Verseils; P. Foury-Leylekian; V. Balédent

arXiv · 2610.38966

Coexistence of superconductivity and magnetic order in BaFe$_2$S$_3$: evidence for orbital-selective delocalization

Y. Oubaid·N. S. Dhami·P. Fertey·C. V. Colin·C. Ritter·A. Forget·D. Bounoua·J. -P. Rueff·M. Verseils·P. Foury-Leylekian·V. Balédent

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Abstract

Understanding how superconductivity emerges from correlated electronic states is a central challenge in condensed matter physics. The quasi-one-dimensional spin-ladder compound \bfs\ serves as a unique platform to study this interplay, as it lacks the two-dimensional square lattice characteristic of most iron-based superconductors. Here, we combine high-pressure x-ray and neutron diffraction, x-ray emission spectroscopy, and electrical transport to map its structural, magnetic, and electronic evolution into the superconducting regime. We \revised{observe} a striking pressure-induced decoupling: while the long-range stripe-type antiferromagnetic order remains remarkably robust under pressure up to the onset of superconductivity, the local iron magnetic moment is suppressed by nearly 80\%. This dichotomy \revised{points to an orbital-selective mechanism}, where specific Fe $3d$ electrons remain localized to sustain magnetism while others delocalize to form the itinerant and superconducting state. \revised{Superconductivity emerges while long-range magnetic order is still present, revealing that the two coexist in \bfs, which we attribute to} the selective response of multiorbital electronic degrees of freedom.

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Y. Oubaid, N. S. Dhami, P. Fertey, C. V. Colin, C. Ritter, A. Forget, D. Bounoua, J. -P. Rueff, M. Verseils, P. Foury-Leylekian, V. Balédent. 2026-10-28. Coexistence of superconductivity and magnetic order in BaFe$_2$S$_3$: evidence for orbital-selective delocalization. https://arxiv.org/abs/2610.38966

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