Rotation of reflectivity anisotropy due to uniaxial strain along [110](tetr) in the electron-doped Fe-based superconductor Ba(Fe0.955Co0.045)(2)As-2

Abstract

©2020 American Physical Society. We present a strain-dependent time-resolved reflectometry experiment on Ba(Fe0.955Co0.045)(2)As-2 in the nematic state. Uniaxial external pressure has usually been applied to obtain a single nematic domain. However, reflectivity with and without pumping under uniaxial strain along [110](tetr) reveals an unexpected nematicity of which C-4 symmetry-breaking orientation is rotated by 20 degrees. Our observation suggests a microscopic coexistence of B-2g and B-1g nematicity under uniaxial strain and possibly of an XY-type nematic order in the electron-doped iron pnictide