Iron Displacements and Magnetoelastic Coupling in the Spin-Ladder Compound BaFe2Se3

TL;DR

This study reveals long-range antiferromagnetic order and local iron displacements in BaFe2Se3, highlighting strong magnetoelastic coupling and its potential relevance to superconductivity in FeX4-based materials.

Contribution

It demonstrates the coexistence of magnetic order and atomic displacements in BaFe2Se3, emphasizing the role of magnetoelastic coupling in these compounds.

Findings

Long-range antiferromagnetic order below 256 K

Presence of local iron displacements

Strong magnetoelastic coupling observed

Abstract

We report long-range ordered antiferromagnetism concomitant with local iron displacements in the spin-ladder compound BaFe$_2$Se$_3$. Short-range magnetic correlations, present at room temperature, develop into long-range antiferromagnetic order below T$_N$ = 256 K, with no superconductivity down to 1.8 K. Built of ferromagnetic Fe$_4$ plaquettes, the magnetic ground state correlates with local displacements of the Fe atoms. These iron displacements imply significant magnetoelastic coupling in FeX$_4$-based materials, an ingredient hypothesized to be important in the emergence of superconductivity. This result also suggests that knowledge of these local displacements is essential for properly understanding the electronic structure of these systems. As with the copper oxide superconductors two decades ago, our results highlight the importance of reduced dimensionality spin ladder compounds in the study of the coupling of spin, charge, and atom positions in superconducting materials.