# Charge carrier dynamics of FeSe thin film investigated by terahertz magneto-optical spectroscopy

## TL;DR

This study uses terahertz magneto-optical spectroscopy to analyze charge carrier dynamics in FeSe thin films, revealing temperature-dependent changes in carrier densities and scattering times related to electronic nematic phase transitions.

## Contribution

It provides detailed quantitative analysis of electron and hole carriers in FeSe thin films using a two-carrier Drude model across various temperatures.

## Key findings

- Hole density decreases below structural transition temperature.
- Electron density increases below structural transition temperature.
- Hole scattering time becomes longer than electron scattering time at low temperatures.

## Abstract

We performed terahertz magneto-optical spectroscopy of FeSe thin film to elucidate the charge carrier dynamics. The measured diagonal (longitudinal) and off-diagonal (Hall) conductivity spectra are well reproduced by two-carrier Drude model, from which the carrier densities, scattering times and effective masses of electron and hole carriers are determined in a wide range of temperature. The hole density decreases below the structural transition temperature while electron density increases, which is attributed to the band structure modification in the electronic nematic phase. The scattering time of the hole carrier becomes substantially longer than that of the electron at lower temperature, which accounts for the increase of the positive dc Hall coefficient at low temperature.