Phase Separation and Superconductivity in Fe1+xTe0.5Se0.5

TL;DR

This study reveals that in Fe1+xTe0.5Se0.5, phase separation enhances superconductivity, with homogeneous ordering suppressing it, highlighting the importance of structural heterogeneity in iron-based superconductors.

Contribution

The paper demonstrates that phase separation, rather than homogeneous ordering, promotes higher superconducting volume fractions in Fe1+xTe0.5Se0.5.

Findings

Superconductivity is maximized in phase-separated structures.

Homogeneous ordering hinders superconductivity.

Structural heterogeneity correlates with higher superconducting volume fractions.

Abstract

Fe1+xTe0.5Se0.5 is the archetypical iron-based superconductor. Here we show that the superconducting state is controlled by the stacking of its anti-PbO layers, such that homogeneous ordering hinders superconductivity and the highest volume fractions are observed in phase separated structures as evidenced by either a distribution of lattice parameters or microstrain.