In-plane electronic anisotropy in underdoped Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$ revealed by detwinning in a magnetic field

TL;DR

This study demonstrates that a magnetic field can partially detwin underdoped Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$, revealing significant in-plane electronic anisotropy driven by magneto-elastic coupling, indicating an electronic origin of lattice distortion.

Contribution

It provides direct evidence of magnetic field-induced detwinning and highlights the electronic origin of lattice distortion in underdoped iron pnictides.

Findings

Magnetic field causes partial detwinning in underdoped Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$

Significant in-plane electronic anisotropy observed in detwinned samples

Electronic anisotropy is smaller resistivity along the antiferromagnetic direction

Abstract

We present results of angle-dependent magnetoresistance measurements and direct optical images of underdoped Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$ which reveal partial detwinning by action of a 14T magnetic field. Driven by a substantial magneto-elastic coupling, this result provides evidence for an electronic origin of the lattice distortion in underdoped iron pnictides. The observed anisotropy in these partially detwinned samples implies a substantial in-plane electronic anisotropy in the broken symmetry state, with a smaller resistivity along the antiferromagnetic ordering direction.