Universal stripe order as a precursor of the superconducting phase in pressurized BaFe2Se3 Spin Ladder
Résumé
Abstract It has been recently observed that a superconducting phase emerges under pressure in the Fe-based spin-ladders BaFe 2 X 3 (X = S, Se). The low dimensionality of the Fe spin-ladders, which simplifies the elaboration of theoretical models, should help to understand the mechanism of superconductivity. We investigate here the frontier between magnetic and superconducting (SC) phases in BaFe 2 Se 3 by performing challenging powder neutron diffraction (PND) and Fe K β x-ray emission spectroscopy (XES) under high pressure. We show that the ambient pressure ground state with a block-like magnetic order is destabilized under pressure. A pressure-induced antiferromagnetic stripe-like spin order, similar to the magnetic order of the parent superconductor BaFe 2 S 3 , is observed above 3-4 GPa. Our discovery shows that the stripe magnetic order is a key phase close to the SC dome and its particular magnetic fluctuations could be involved in the stabilization of superconductivity in Fe-based spin ladders.
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