Unabridged phase diagram for single-phased FeSexTe1-x thin films

TL;DR

This study presents a comprehensive phase diagram for FeSexTe1-x thin films, revealing a single superconducting dome with a maximum Tc of 20 K, advancing understanding of iron-based superconductivity.

Contribution

First complete phase diagram for FeSexTe1-x thin films across full Se doping range, showing a single superconducting dome and high Tc in a new domain.

Findings

Maximum Tc of 20 K in Se content 0.6-0.8

All films retain tetragonal structure at room temperature

First single-phased superconducting dome in iron chalcogenides

Abstract

A complete phase diagram and its corresponding physical properties are essential prerequisites to understand the underlying mechanism of iron based superconductivity. For the structurally simplest 11 (FeSeTe) system, earlier attempts using bulk samples have not been able to do so due to the fabrication difficulties. Here, thin FeSexTe1-x films with the Se content covering the full range were fabricated by using pulsed laser deposition method. Crystal structure analysis shows that all films retain the tetragonal structure in room temperature. Significantly, the highest superconducting transition temperature (TC = 20 K) occurs in the newly discovered domain, 0.6 - 0.8. The single-phased superconducting dome for the full Se doping range is the first of its kind in iron chalcogenide superconductors. Our results present a new avenue to explore novel physics as well as to optimize superconductors.