Block magnetism coupled with local distortion in the iron-based spin-ladder compound BaFe2Se3

TL;DR

This study investigates the magnetic properties of the insulating BaFe2Se3, revealing a unique block magnetic structure with strong magnetoelastic coupling and a transition at approximately 255 K.

Contribution

It uncovers a novel block magnetic order in BaFe2Se3 and demonstrates its coupling with local structural distortions, expanding understanding of magnetism in iron-based compounds.

Findings

Long-range magnetic order established below 255 K

Magnetic moments form Fe4 ferromagnetic units

Magnetoelastic coupling causes significant structural distortion

Abstract

Magnetism in the insulating BaFe$_2$Se$_3$ was examined through susceptibility, specific heat, resistivity and neutron diffraction measurements. After formation of a short-range magnetic correlation, a long-range ordering was observed below $T_{\rm N}\sim 255$ K. The transition is obscured by bulk properties. Magnetic moments ($\parallel a$) are arranged to form a Fe$_4$ ferromagnetic unit, and each Fe$_4$ stacks antiferromagnetically. This block magnetism is of the third type among magnetic structures of ferrous materials. The magnetic ordering drives unusually large distortion via magnetoelastic coupling.