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.
@article{arxiv.1702.02088,
title = {Anomalous temperature evolution of the electronic structure of FeSe},
author = {Y. Kushnirenko and A. A. Kordyuk and A. Fedorov and E. Haubold and T. Wolf and B. Büchner and S. V. Borisenko},
journal= {arXiv preprint arXiv:1702.02088},
year = {2017}
}