Anisotropic charge dynamics in detwinned Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$

TL;DR

This study explores the anisotropic charge dynamics in detwinned Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$ using polarized optical conductivity measurements, revealing the role of orbital order in structural transitions.

Contribution

It provides new insights into the orbital order's influence on charge dynamics and anisotropy in iron-based superconductors through detailed optical measurements.

Findings

Charge dynamics are anisotropic and track dc transport properties.

Dichroism extends to high frequencies, indicating orbital order effects.

Results support orbital order's role in structural phase transition.

Abstract

We investigate the optical conductivity as a function of temperature with light polarized along the in-plane orthorhombic $a$- and $b$-axes of Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$ for $x$=0 and 2.5$\%$ under uniaxial pressure. The charge dynamics at low frequencies on these detwinned, single domain compounds tracks the anisotropic $dc$ transport properties across their structural and magnetic phase transitions. Our findings allow us to estimate the dichroism, which extends to relatively high frequencies. These results are consistent with a scenario in which orbital order plays a significant role in the tetragonal-to-orthorhombic structural transition.