[(Li0.8Fe0.2)OH]FeS and the ferromagnetic superconductors [(Li0.8Fe0.2)OH]Fe(S1-xSex) (0<x<1)

TL;DR

This study synthesizes and characterizes [(Li0.8Fe0.2)OH]FeS and its selenium-doped series, revealing how chemical pressure from sulfur doping suppresses superconductivity while ferromagnetism persists, highlighting the interplay between magnetism and superconductivity.

Contribution

It provides new insights into how sulfur doping affects superconductivity and ferromagnetism in [(Li0.8Fe0.2)OH]FeS compounds through chemical pressure effects.

Findings

Sulfur doping decreases the critical temperature of superconductivity.

Superconductivity is completely suppressed in sulfur-rich compositions.

Ferromagnetism in hydroxide layers persists despite doping.

Abstract

[(Li0.8Fe0.2)OH]FeS and the series [(Li0.8Fe0.2)OH]Fe(S1-xSex) (0<x<1) were synthesized by hydrothermal methods and characterized by X-ray single crystal and powder diffraction, EDX and chemical analysis. Selenium-rich compounds show the coexistence of magnetic ordering with superconductivity known from the pure selenium compound. Sulphur doping decreases the critical temperature through chemical pressure until superconductivity is completely absent in [(Li0.8Fe0.2)OH]FeS, while the ferromagnetism in the [(Li0.8Fe0.2)OH] layers persists. The Li:Fe ratio in the hydroxide layer, and thus the charge transfer of 0.2 electrons from the hydroxide to the iron chalcogenide layers remains unchanged in [(Li0.8Fe0.2)OH]Fe(S1-xSex), which indicates that the chemical pressure effect of the smaller sulphide ions impedes superconductivity in [(Li0.8Fe0.2)OH]FeS