Evidence for an electron nematic phase transition in underdoped iron pnictide superconductors

TL;DR

This study provides evidence for an electron nematic phase transition in underdoped iron pnictide superconductors, showing that electronic anisotropy drives structural changes before magnetic order appears.

Contribution

It demonstrates that the structural transition in Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$ is primarily electronic, revealing an electron nematic phase transition in these materials.

Findings

Significant in-plane resistivity anisotropy observed

Structural transition is electronically driven

Nematic phase precedes magnetic order

Abstract

Electrical resistivity measurements of detwinned single crystals of the representative iron arsenide Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$ reveal a dramatic in-plane anisotropy associated with the tetragonal-to-orthorhombic structural transition that precedes the onset of long-range antiferromagnetic order. These results indicate that the structural transition in this family of compounds is fundamentally electronic in origin.