Reflection anisotropy experiments to study non-equilibrium dynamics of electronic nematicity

TL;DR

This paper introduces a new experimental approach to study the non-equilibrium dynamics of electronic nematicity through reflectivity anisotropy measurements, demonstrating its reliability and effects of photo-excitation.

Contribution

The study develops and validates a novel method for investigating electronic nematicity and its dynamics, including time-resolved measurements under photo-excitation.

Findings

Broken four-fold symmetry observed in Ba(Fe,Co)2As2

Method reliably detects reflectivity anisotropy

Photo-excitation suppresses nematic order anisotropy

Abstract

Electronic nematicity have attracted a great deal of interest in the unconventional superconductivity research. We present an experimental method to investigate reflectivity anisotropy by the electronic nematicity and its non-equilibrium dynamics. Our experimental results on Ba(Fe$_{0.955}$Co$_{0.045}$)$_{2}$As$_{2}$ single crystal clearly feature the broken four-fold symmetry along directions parallel to Fe-Fe bonding. Numerical simulations using WVASE from Woollam Co. demonstrate that our method is highly reliable under various experimental conditions. Finally, we perform time-resolved reflectivity anisotropy measurement confirming that photo-excitation by 1.55 eV photons suppresses the reflectivity anisotropy due to nematic order.