Fragility of Topology under Electronic Correlations in Iron Chalcogenides

TL;DR

This study reveals that the non-trivial topological properties in iron chalcogenides are fragile and can be significantly affected by electronic correlations, especially the orbital-selective Mott phase, as shown through spectroscopic analysis.

Contribution

We demonstrate how electronic correlations, particularly the orbital-selective Mott phase, influence and can destabilize topological surface states in FeTe1-xSex.

Findings

Topological phase transition occurs between x=0.04 and x=0.09 selenium content.

Topological surface state coherence deteriorates at high temperatures due to OSMP.

Non-trivial topology remains fragile under strong electronic correlations.

Abstract

The interplay between electronic correlations and topology is a central topic in the study of quantum materials. In this work, we investigate the impact of the orbital-selective Mott phase (OSMP) on the topological properties of FeTe1-xSex (FTS), an iron chalcogenide superconductor known to host both non-trivial Z2 topology and strong electronic correlations. Using angle-resolved photoemission spectroscopy, we track the evolution of topological surface states across various doping levels and temperatures. We identify a topological phase transition between trivial and non-trivial topology as a function of selenium content, with critical behavior observed between x = 0.04 and x = 0.09. Additionally, we find that at elevated temperatures, the coherence of the topological surface state deteriorates due to the emergence of OSMP, despite the topological invariant remaining intact. Our results demonstrate that the non-trivial topology in iron chalcogenide is fragile under strong electronic correlations.