# Robust short-range-ordered nematicity in FeSe evidenced by high-pressure NMR

## TL;DR

This study uses high-pressure NMR to reveal long-lived, inhomogeneous electronic nematicity in FeSe that persists over a wide temperature range and is robust against pressure, offering new insights into nematic fluctuations in iron-based superconductors.

## Contribution

It provides direct evidence of long-lived, short-range-ordered nematicity in FeSe under high pressure, expanding understanding of nematic fluctuations in iron-based superconductors.

## Key findings

- NMR linewidth broadening indicates inhomogeneous nematicity
- Nematic order persists up to eight times the structural transition temperature
- Nematicity remains robust against pressure changes

## Abstract

We report high-pressure $^{77}$Se NMR studies on FeSe single crystals that reveal a prominent inhomogeneous NMR linewidth broadening upon cooling, with the magnetic field applied along the tetragonal [110] direction. The data indicate the existence of short-range-ordered, inhomogeneous electronic nematicity, which has surprisingly long time scales over milliseconds. The short-range order survives temperatures up to $8$ times the structural transition temperature, and remains robust against pressure, in contrast to the strong pressure-dependence of the orbital ordering, structural transition, and the ground state magnetism. Such an extended region of static nematicity in the ($P$,$T$) space of FeSe indicates an enormously large fluctuating regime, and provide fresh insights and constraints to the understanding of electronic nematicity in iron-based superconductors.