Bandwidth controlled insulator-metal transition in BaFe$_2$S$_3$: A M\"ossbauer study under pressure

TL;DR

This study uses synchrotron Mössbauer spectroscopy to explore how pressure induces an insulator-metal transition and suppresses magnetic order in BaFe₂S₃, revealing a local magnetic phase diagram and a first-order phase transition.

Contribution

First local magnetic phase diagram of BaFe₂S₃ under pressure, showing detailed magnetic behavior and phase transition characteristics.

Findings

Magnetic ordering temperature increases up to 185 K at 7.5 GPa.

Magnetic order is fully suppressed at 9.9 GPa.

First-order phase transition indicated by a sudden drop in hyperfine field.

Abstract

BaFe$_2$S$_3$ is a quasi one-dimensional Mott insulator that orders antiferromagnetically below 117(5)\,K. The application of pressure induces a transition to a metallic state, and superconductivity emerges. The evolution of the magnetic behavior on increasing pressure has up to now been either studied indirectly by means of transport measurements, or by using local magnetic probes only in the low pressure region. Here, we investigate the magnetic properties of BaFe$_2$S$_3$ up to 9.9\,GPa by means of synchrotron $^{57}$Fe M\"ossbauer spectroscopy experiments, providing the first local magnetic phase diagram. The magnetic ordering temperature increases up to 185(5) K at 7.5\,GPa, and is fully suppressed at 9.9\,GPa. The low-temperature magnetic hyperfine field is continuously reduced from 12.9 to 10.3\,T between 1.4 and 9.1\,GPa, followed by a sudden drop to zero at 9.9\,GPa indicating a first-order phase transition. The pressure dependence of the magnetic order in BaFe$_2$S$_3$ can be qualitatively explained by a combination of a bandwidth-controlled insulator-metal transition as well as a pressure enhanced exchange interaction between Fe-atoms and Fe 3\textit{d}-S 3\textit{p} hybridization.