# Disorder-Induced Electronic Nematicity

## TL;DR

This paper develops a theoretical framework showing how disorder can locally induce nematic order in materials with strong nematic fluctuations, explaining recent experimental observations in iron-based superconductors.

## Contribution

It introduces a symmetry-based Ginzburg-Landau model and microscopic calculations to explain disorder-induced nematicity and its enhancement of the transition temperature.

## Key findings

- Single impurities induce local nematicity above the transition temperature.
- Disorder causes inhomogeneous nematicity with zero spatial average.
- Finite disorder can enhance the nematic transition temperature.

## Abstract

We expose the theoretical mechanisms underlying disorder-induced nematicity in systems exhibiting strong fluctuations or ordering in the nematic channel. Our analysis consists of a symmetry-based Ginzburg-Landau approach and associated microscopic calculations. We show that a single featureless point-like impurity induces nematicity locally, already above the critical nematic transition temperature. The persistence of fourfold rotational symmetry constrains the resulting disorder-induced nematicity to be inhomogeneous and spatially average to zero. Going beyond the single impurity case, we discuss the effects of finite disorder concentrations on the appearance of nematicity. We identify the conditions that allow disorder to enhance the nematic transition temperature, and we provide a concrete example. The presented theoretical results can explain a large series of recent experimental discoveries of disorder-induced nematic order in iron-based superconductors.