# Strongly enhanced temperature dependence of the chemical potential in FeSe

## TL;DR

This study combines theoretical modeling and experimental ARPES data to reveal a significantly larger temperature-dependent shift in the chemical potential of FeSe than previously expected, impacting understanding of its superconductivity.

## Contribution

The paper introduces a new set of tight binding parameters fitted to ARPES data and demonstrates a large temperature-dependent chemical potential shift in FeSe.

## Key findings

- Observed a ~25 meV chemical potential shift between 100 K and 300 K
- Predicted a 10 meV shift using tight binding model
- Implications for models of superconductivity and nematic order in FeSe

## Abstract

Employing a 10-orbital tight binding model, we present a new set of hopping parameters fitted directly to our latest high resolution angle-resolved photoemission spectroscopy (ARPES) data for the high temperature tetragonal phase of FeSe. Using these parameters we predict a large 10 meV shift of the chemical potential as a function of temperature. In order to confirm this large temperature dependence, we performed ARPES experiments on FeSe and observed a $\sim$25 meV rigid shift to the chemical potential between 100 K and 300 K. This unexpectedly strong shift has important implications for theoretical models of superconductivity and of nematic order in FeSe materials.