Charge dynamics of the spin-density-wave state in BaFe$_2$As$_2$

TL;DR

This study uses optical methods to analyze the charge dynamics and pseudogap formation in BaFe$_2$As$_2$ during its spin-density-wave transition at 135 K, revealing partial spectral weight redistribution and reduced scattering.

Contribution

It provides detailed optical characterization of BaFe$_2$As$_2$'s SDW phase transition, highlighting pseudogap features and changes in charge carrier scattering.

Findings

Depletion in far infrared optical conductivity below T_SDW

Formation of a pseudogap-like feature in excitation spectrum

Approximately 20% spectral weight affected by SDW transition

Abstract

We report on a thorough optical investigation of BaFe$_2$As$_2$ over a broad spectral range and as a function of temperature, focusing our attention on its spin-density-wave (SDW) phase transition at $T_{SDW}=135$ K. While BaFe$_2$As$_2$ remains metallic at all temperatures, we observe a depletion in the far infrared energy interval of the optical conductivity below $T_{SDW}$, ascribed to the formation of a pseudogap-like feature in the excitation spectrum. This is accompanied by the narrowing of the Drude term consistent with the $dc$ transport results and suggestive of suppression of scattering channels in the SDW state. About 20% of the spectral weight in the far infrared energy interval is affected by the SDW phase transition.