Control of tetrahedral coordination and superconductivity in FeSe0.5Te0.5 thin films

TL;DR

This study shows how controlling the tetrahedral structure in FeSe0.5Te0.5 thin films influences superconductivity, highlighting the importance of tetrahedral dimensions and stress-induced distortions.

Contribution

It demonstrates the use of epitaxial thin film growth to systematically manipulate tetrahedral geometry and study its effect on superconductivity in Fe-based materials.

Findings

Superconductivity correlates with tetrahedral dimensions.

Biaxial stress alters tetrahedral geometry.

Se/Te height is crucial for superconductivity.

Abstract

We demonstrate a close relationship between superconductivity and the dimensions of the Fe-Se(Te) tetrahedron in FeSe0.5Te0.5. This is done by exploiting thin film epitaxy, which provides controlled biaxial stress, both compressive and tensile, to distort the tetrahedron. The Se/Te height within the tetrahedron is found to be of crucial importance to superconductivity, in agreement with the theoretical proposal that (pi,pi) spin fluctuations promote superconductivity in Fe superconductors.