Spectral weight transfer in strongly correlated Fe$_{1.03}$Te

TL;DR

This study investigates how the optical conductivity and spectral weight transfer in Fe$_{1.03}$Te change across its magnetic transition, revealing increased carrier concentration and modifications in electronic structure.

Contribution

It provides detailed analysis of spectral weight transfer and electronic structure changes in Fe$_{1.03}$Te across the magnetic transition, highlighting the role of pseudogap closure and effective mass decrease.

Findings

Spectral weight shifts from high to low frequency below T_N.

Increase in plasma frequency due to higher carrier concentration.

Evidence of pseudogap closure on the electron pocket.

Abstract

The temperature dependence of the in-plane optical conductivity has been determined for Fe$_{1.03}$Te above and below the magnetic and structural transition at $T_N\simeq 68$ K. The electron and hole pockets are treated as two separate electronic subsystems; a strong, broad Drude response that is largely temperature independent, and a much weaker, narrow Drude response with a strong temperature dependence. Spectral weight is transferred from high to low frequency below $T_N$, resulting in the dramatic increase of both the low-frequency conductivity and the related plasma frequency. The change in the plasma frequency is due to an increase in the carrier concentration resulting from the closing of the pseudogap on the electron pocket, as well as the likely decrease of the effective mass in the antiferromagnetic state.