# Anomalous high-magnetic field electronic state of the nematic superconductors FeSe$_{1-x}$S$_x$

## TL;DR

This study reveals that the nematic electronic state in FeSe$_{1-x}$S$_x$ superconductors exhibits anomalous non-Fermi liquid behavior with unusual resistivity and magnetoresistance, influenced by magnetic fields, disorder, and electronic structure changes.

## Contribution

It provides detailed high-field transport measurements showing the non-Fermi liquid nature and anomalous scattering in the nematic phase of FeSe$_{1-x}$S$_x$, highlighting new insights into its electronic state.

## Key findings

- Nematic state shows linear resistivity at low temperatures.
- Resistivity exhibits a $T^{1.5}$ dependence near the nematic end point.
- Magnetoresistance follows an $H^{1.55}$ dependence with an unusual low-temperature peak.

## Abstract

Understanding superconductivity requires detailed knowledge of the normal electronic state from which it emerges. A nematic electronic state that breaks the rotational symmetry of the lattice can potentially promote unique scattering relevant for superconductivity. Here, we investigate the normal transport of superconducting FeSe$_{1-x}$S$_x$ across a nematic phase transition using high magnetic fields up to 69 T to establish the temperature and field-dependencies. We find that the nematic state is an anomalous non-Fermi liquid, dominated by a linear resistivity at low temperatures that can transform into a Fermi liquid, depending on the composition $x$ and the impurity level. Near the nematic end point, we find an extended temperature regime with $T^{1.5}$ resistivity. The transverse magnetoresistance inside the nematic phase has as a $H^{1.55}$ dependence over a large magnetic field range and it displays an unusual peak at low temperatures inside the nematic phase. Our study reveals anomalous transport inside the nematic phase, driven by the subtle interplay between the changes in the electronic structure of a multi-band system and the unusual scattering processes affected by large magnetic fields and disorder