Normal state bottleneck and nematic fluctuations from femtosecond quasi-particle relaxation dynamics in Sm(Fe,Co)AsO

TL;DR

This study uses femtosecond spectroscopy to explore quasiparticle relaxation in electron-doped Sm(Fe,Co)AsO, revealing a normal state pseudogap and nematic fluctuations similar to other iron pnictides, indicating common electronic nematicity features.

Contribution

It demonstrates that nematic fluctuations and pseudogap phenomena are present in Sm(Fe,Co)AsO, extending the understanding of electronic nematicity across different iron pnictide families.

Findings

Presence of a normal state pseudogap in Sm(Fe,Co)AsO.

Observation of 2-fold symmetry breaking indicating nematicity.

Similarity of dynamics to Ba(Fe,Co)_{2}As_{2}.

Abstract

We investigate temperature and fluence dependent dynamics of the photoexcited quasi-particle relaxation and low-energy electronic structure in electron-doped 1111-structure Sm(Fe_{0.93}Co_{0.07})AsO single crystal. We find that the behavior is qualitatively identical to the 122-structure Ba(Fe,Co)_{2}As_{2} including the presence of a normal state pseudogap and a marked 2-fold symmetry breaking in the tetragonal phase that we relate to the electronic nematicity. The 2-fold symmetry breaking appears to be a general feature of the electron doped iron pnictides.