Anomalous temperature evolution of the electronic structure of FeSe

TL;DR

This study uses ARPES to investigate FeSe across a wide temperature range, revealing unusual temperature-dependent shifts in electronic structure that challenge conventional expectations and provide insights into high-temperature superconductivity.

Contribution

It uncovers anomalous temperature evolution of FeSe's electronic structure, showing a relaxation towards band structure predictions upon warming, contrary to typical behavior.

Findings

Pronounced dispersion shifts on the order of hundreds of kelvins.

Band structure tends to relax to theoretical predictions with increasing temperature.

Insights into the interactions influencing high-temperature superconductivity.

Abstract

We present ARPES data taken from the structurally simplest representative of iron-based superconductors, FeSe, in a wide temperature range. Apart from the variations related to the nematic transition, we detect very pronounced shifts of the dispersions on the scale of hundreds of kelvins. Remarkably, upon warming the sample up, the band structure has a tendency to relax to the one predicted by conventional band structure calculations, right opposite to what is intuitively expected. Our findings shed light on the origin of the dominant interaction shaping the electronic states responsible for high-temperature superconductivity in iron-based materials.