Correlation between superconductivity and antiferromagnetism in Rb0.8Fe2Se2-xTex single crystals

TL;DR

This study demonstrates that substituting Te for Se in Rb0.8Fe2Se2-xTex single crystals suppresses both superconductivity and antiferromagnetism, revealing their close correlation and tunability via lattice expansion.

Contribution

It provides the first experimental evidence linking superconductivity and antiferromagnetism in Rb0.8Fe2Se2-xTex through isovalent substitution under negative chemical pressure.

Findings

Superconducting transition temperature (Tc) decreases with Te substitution.

Neel temperature (TN) is suppressed as lattice expands.

Superconductivity is fully suppressed near x=0.3, turning the material semiconducting.

Abstract

We report the first experimental evidence for the intimate connection between superconductivity and antiferromagnetism in Rb0.8Fe2Se2-xTex single crystal under negative chemical pressure by substituting Se with isovalent Te atoms. Electrical resistance measurements in the temperature range from 4 K to 550 K demonstrate that both superconducting transition temperature (Tc) and Neel temperature (TN) were suppressed continuously with the lattice expansion. When the Te concentration x in Rb0.8Fe2Se2-xTex approaches 0.3, the superconducting transition temperature Tc is completely suppressed and the sample behaves like a semiconductor, meanwhile the characteristic peak of antiferromagnetic transition on resistance curve disappears. Our observation suggests that the pressure-induced lattice expansion can be used to tune the correlativity of superconductivity and antiferromagnetism.