The magnetic precursor of the pressure-induced superconductivity in Fe-ladder compound

TL;DR

This study investigates how pressure influences magnetic orders in iron-based ladder compounds, revealing a magnetic precursor phase in BaFe$_2$S$_3$ that is closely related to the emergence of superconductivity.

Contribution

It uncovers a magnetic precursor phase in BaFe$_2$S$_3$ under pressure, linking magnetic transitions to the onset of pressure-induced superconductivity.

Findings

BaFe$_2$S$_3$ exhibits a quantum phase transition with increased Néel temperature under pressure.

The magnetic order in BaFe$_2$S$_3$ remains unchanged, but an orbital selective Mott phase develops.

Pressure has contrasting effects on CsFe$_2$Se$_3$ and BaFe$_2$S$_3$, despite similar structures.

Abstract

The pressure effects on the antiferromagentic orders in iron-based ladder compounds CsFe$_2$Se$_3$ and BaFe$_2$S$_3$ have been studied using neutron diffraction. With identical crystal structure and similar magnetic structures, the two compounds exhibit highly contrasting magnetic behaviors under moderate external pressures. In CsFe$_2$Se$_3$ the ladders are brought much closer to each other by pressure, but the stripe-type magnetic order shows no observable change. In contrast, the stripe order in BaFe$_2$S$_3$, undergoes a quantum phase transition where an abrupt increase of N$\acute{e}$el temperature by more than 50$\%$ occurs at about 1 GPa, accompanied by a jump in the ordered moment. With its spin structure unchanged, BaFe$_2$S$_3$ enters an enhanced magnetic phase that bears the characteristics of an orbital selective Mott phase, which is the true neighbor of superconductivity emerging at higher pressures.