Revised Phase Diagram for FeTe1-xSex system with less excess Fe atoms

TL;DR

This study reveals that annealing reduces excess Fe in FeTe1-xSex crystals, enabling bulk superconductivity and revealing a phase diagram similar to other iron-based superconductors, with coexistence of superconductivity and antiferromagnetism.

Contribution

The paper provides a revised phase diagram for FeTe1-xSex with less excess Fe, showing coexistence of superconductivity and antiferromagnetism, and suggests a universal phase diagram for iron-based superconductors.

Findings

Bulk superconductivity appears after annealing reduces excess Fe.

Superconductivity coexists with antiferromagnetic order in certain compositions.

The phase diagram resembles that of other iron-based superconductors.

Abstract

We observed bulk superconductivity in the FeTe1-xSex crystals with a low Se concentration after the excess Fe atoms existing unavoidably in crystals as-grown are partially removed by means of annealing in the air. A revised magnetism and superconductivity phase diagram is obtained via resistivity and magnetic susceptibility measurements for FeTe1-xSex system. It is found that bulk superconductivity coexists with antiferromagnetic order in the crystals with 0.05<x<0.20. The phase diagram is very similar to the case of the K-doping or Co-doping BaFe2As2, as well as of SmFeAsO1-xFx iron-pnictide system, perhaps indicating that all iron-based systems have a generic phase diagram, although antiferromagnetic wave vector in the parent compounds of these systems is remarkable different.