Anomalous momentum dependence of the multiband electronic structure of FeSe_1-xTe_x superconductors induced by atomic disorder

TL;DR

This study investigates how atomic disorder in FeSe_1-xTe_x superconductors causes orbital-selective anomalies in electronic band dispersion, revealing complex effects of structural disorder on electronic properties.

Contribution

It demonstrates that chalcogen height disorder induces orbital-selective band dispersion changes, not just simple obscuration, in FeSe_1-xTe_x superconductors.

Findings

Disorder affects Fe 3d band dispersions in an orbital-selective manner.

Chalcogen height disorder reverses Fe 3d level splitting.

Splitting of the hole band with Fe 3d x^2-y^2 character observed.

Abstract

When periodicity of crystal is disturbed by atomic disorder, its electronic state becomes inhomogeneous and band dispersion is obscured. In case of Fe-based superconductors, disorder of chalcogen/pnictogen height causes disorder of Fe 3d level splitting. Here, we report an angle-resolved photoemission spectroscopy study on FeSe_1-xTe_x with the chalcogen height disorder, showing that the disorder affects the Fe 3d band dispersions in an orbital-selective way instead of simple obscuring effect. The reverse of the Fe 3d level splitting due to the chalcogen height difference causes the splitting of the hole band with Fe 3d x^2-y^2 character around the Gamma point.