paper

Nematic correlation length in iron-based superconductors probed by inelastic x-ray scattering

arXiv:2001.01343 · doi:10.1103/PhysRevLett.124.157001

Abstract

Nematicity is ubiquitous in electronic phases of high- $T_{c}$ superconductors, particularly in the Fe-based systems. We used inelastic x-ray scattering to extract the temperature-dependent nematic correlation length $I^¾$ from the anomalous softening of acoustic phonon modes in FeSe, underdoped Ba(Fe $_{0.97}$ Co $_{0.03}$ ) $_{2}$ As $_{2}$ and optimally doped Ba(Fe $_{0.94}$ Co $_{0.06}$ ) $_{2}$ As $_{2}$ . In all cases, we find that $I^¾$ is well described by a power law $(T - T_{0})^{- 1/2}$ extending over a wide temperature range. We attributed this mean-field behavior and the extended fluctuation regime to a sizable nemato-elastic coupling, which may be detrimental to superconductivity.