Nanoscale electronic order in iron pnictides

TL;DR

This study reveals nanoscale electronic heterogeneity in iron pnictides, showing coexistence of different charge environments in underdoped samples, which impacts understanding of magnetism and superconductivity interplay.

Contribution

It provides direct evidence of nanoscale charge order in iron pnictides using nuclear quadrupole resonance, highlighting local electronic heterogeneity.

Findings

Undoped and optimally-doped compounds show a single charge environment.

Underdoped compounds exhibit two distinct charge environments.

Nanoscale coexistence of low- and high-doping-like regions is observed.

Abstract

The charge distribution in RFeAsO$_{1-x}$F$_x$ (R=La, Sm) iron pnictides is probed using As nuclear quadrupole resonance. Whereas undoped and optimally-doped or overdoped compounds feature a single charge environment, two charge environments are detected in the underdoped region. Spin-lattice relaxation measurements show their coexistence at the nanoscale. Together with the quantitative variations of the spectra with doping, they point to a local electronic order in the iron layers, where low- and high-doping-like regions would coexist. Implications for the interplay of static magnetism and superconductivity are discussed.