Elasto-Raman scattering: Arsenic optical phonon as a probe of nematicity in BaFe2As2

Nematicity in the iron-based superconductor parent compound BaFe${}_{2}$As${}_{2}$ is studied using Raman scattering under tunable uniaxial strain. The authors use the polarization-resolved arsenic phonon intensity to monitor the nematic order parameter as a function of both temperature and strain. This elasto-Raman approach showcases the interest of combining anisotropic strain with a symmetry-resolved probe such as Raman scattering. It can be applied to a wide variety of quantum materials where strain can serve as a nonthermal control parameter.