Superconductivity and Antiferromagnetism In Fe(Te1-xSx)y System

TL;DR

This study synthesizes and characterizes Fe(Te1-xSx)y, revealing limited S solubility, superconductivity around 9 K, and coexistence with antiferromagnetism, influenced by excess Fe and potential electronic inhomogeneity.

Contribution

First systematic investigation of superconductivity and antiferromagnetism coexistence in Fe(Te1-xSx)y, highlighting the role of excess Fe and phase inhomogeneity.

Findings

Superconductivity observed at ~9 K in Fe(Te1-xSx)y with x ≤ 0.3

Excess Fe suppresses superconductivity

Coexistence of superconductivity and antiferromagnetism linked to Fe distribution

Abstract

We have synthesized polycrystalline samples and single crystals of Fe(Te1-xSx)y, and characterized their properties. Our results show that the solid solution of S in this system is limited, < 30%. We observed superconductivity at ~ 9 K in both polycrystalline samples Fe(Te1-xSx)y with 0< x <= 0.3 and 0.86 <= y <= 1.0, and single crystals with the composition Fe(Te0.9S0.1)0.91, consistent with the recent report of Tc ~ 10 K superconductivity in the FeTe1-xSx polycrystalline samples with x = 0.1 and 0.2. Furthermore, our systematic studies show that the superconducting properties of this system sensitively depend on excess Fe at interstitial sites and that the excess Fe suppresses superconductivity. Another important observation from our studies is the coexistence of the superconducting phase and antiferromagnetism. Our analyses suggest that this phase coexistence may be associated with the random distribution of excess Fe and possibly occurs in the form of electronic inhomogeneity.