Physical properties of $A_x$Fe$_{2-y}$S$_2$ ($A$=K, Rb and Cs) single crystals

TL;DR

This study synthesizes new Rb and Cs iron sulfide compounds, investigates their physical properties, and finds similarities with related selenide superconductors, revealing insights into their magnetism and resistivity behaviors.

Contribution

The paper reports the synthesis of two new Rb and Cs iron sulfide compounds and systematically investigates their resistivity, magnetism, and thermoelectric properties, highlighting their similarities to known selenide superconductors.

Findings

High temperature resistivity and magnetic anomalies above 500 K.

Discrepancy between ZFC and FC curves in K and Rb compounds.

Similar high-temperature magnetism to $A_x$Fe$_{2-y}$Se$_2$.

Abstract

We successfully synthesized two new compounds Rb$_x$Fe$_{2-y}$S$_2$ and Cs$_x$Fe$_{2-y}$S$_2$ which were isostructural with K$_x$Fe$_{2-y}$Se$_2$ superconductor. We systematically investigated the resistivity, magnetism and thermoelectric power of $A_x$Fe$_{2-y}$S$_2$ ($A$=K, Rb and Cs) single crystals. High temperature resistivity and magnetic measurements show anomalies above 500 K depending on $A$ which are similar to $A_x$Fe$_{2-y}$Se$_2$. Discrepancy between ZFC and FC curves was observed in K$_x$Fe$_{2-y}$S$_2$ and Rb$_x$Fe$_{2-y}$S$_2$, while it disappears in Cs$_x$Fe$_{2-y}$S$_2$. Our results indicate the similar magnetism between $A_x$Fe$_{2-y}$S$_2$ and $A_x$Fe$_{2-y}$Se$_2$ at high temperature.