Evidence of local structural inhomogeneity in FeSe(1-x)Te(x) from extended x-ray absorption fine structure

TL;DR

This study uses EXAFS measurements to reveal local structural inhomogeneities in FeSe(1-x)Te(x), showing distinct local bond lengths and site occupations that influence the electronic properties of these superconductors.

Contribution

It provides direct experimental evidence of local inhomogeneities and site-specific atomic arrangements in FeSe(1-x)Te(x), advancing understanding of their electronic structure.

Findings

Fe-Se and Fe-Te bond lengths differ from average crystallographic distances.

Local bond lengths are similar to those in binary FeSe and FeTe.

Presence of local inhomogeneities and coexisting electronic components.

Abstract

Local structure of FeSe(1-x)Te(x) has been studied by extended x-ray absorption fine-structure (EXAFS) measurements as a function of temperature. Combination of Se and Fe K edge EXAFS has permitted to quantify the local interatomic distances and their mean-square relative displacements. The Fe-Se and Fe-Te bond lengths in the ternary system are found to be very different from the average crystallographic Fe-Se/Te distance, and almost identical to the Fe-Se and Fe-Te distances for the binary FeSe and FeTe systems, indicating distinct site occupation by the Se and Te atoms. The results provide a clear evidence of local inhomogeneities and coexisting electronic components in the FeSe1-xTex, characterized by different local structural configurations, with direct implication on the fundamental electronic structure of these superconductors.