# Room temperature local nematicity in FeSe superconductor

## TL;DR

This study reveals persistent local orthorhombic distortions in FeSe above the structural transition temperature, indicating local nematic fluctuations that influence the macroscopic nematic state in this superconductor.

## Contribution

It provides direct evidence of local nematicity in FeSe at high temperatures, highlighting the role of orbital fluctuations in nematic state formation.

## Key findings

- Local orthorhombic distortion exists above the transition temperature.
- Local distortion magnitude exceeds that at the orthorhombic phase.
- Nematic fluctuations persist up to at least 300 K.

## Abstract

We report pair distribution function measurements of the iron-based superconductor FeSe above and below the structural transition temperature. Structural analysis reveals a local orthorhombic distortion with a correlation length of about 4 nm at temperatures where an average tetragonal symmetry is observed. The analysis further demonstrates that the local distortion is larger than the distortion at temperatures where the average observed symmetry is orthorhombic. Our results suggest that the low-temperature macroscopic nematic state in FeSe forms from an imperfect ordering of orbital-degeneracy-lifted nematic fluctuations which persist up to at least 300 K.