Microstructural analysis of phase separation in iron chalcogenide superconductors

TL;DR

This study uses advanced electron microscopy techniques to analyze phase separation in iron chalcogenide superconductors, revealing that superconductivity is confined to a minor phase with a plate-like morphology.

Contribution

It provides detailed microstructural insights into phase separation in Csx Fe2-ySe2, linking microstructure to superconducting properties.

Findings

Phase separation observed with plate-like minor phase

Superconductivity occurs only in the minority phase

Microstructural analysis correlates composition with superconductivity

Abstract

The interplay between superconductivity, magnetism and crystal structure in iron-based superconductors is a topic of great interest amongst the condensed matter physics community as it is thought to be the key to understanding the mechanisms responsible for high temperature superconductivity. Alkali metal doped iron chalcogenide superconductors exhibit several unique characteristics which are not found in other iron-based superconducting materials such as antiferromagnetic ordering at room temperature, the presence of ordered iron vacancies and high resistivity normal state properties. Detailed microstructural analysis is essential in order to understand the origin of these unusual properties. Here we have used a range of complementary scanning electron microscope based techniques, including high-resolution electron backscatter di raction mapping, to assess local variations in composition and lattice parameter with high precision and sub-micron spatial resolution. Phase separation is observed in the Csx Fe2-ySe2 crystals, with the minor phase distributed in a plate-like morphology throughout the crystal. Our results are consistent with superconductivity occurring only in the minority phase.