Quantitative characterization of short-range orthorhombic fluctuations in FeSe through pair distribution function analysis
- Author(s): Frandsen, BA
- Wang, Q
- Wu, S
- Zhao, J
- Birgeneau, RJ
- et al.
Published Web Locationhttps://doi.org/10.1103/PhysRevB.100.020504
Neutron and x-ray total scattering measurements have been performed on powder samples of the iron chalcogenide superconductor FeSe. Using pair distribution function analysis of the total scattering data to investigate short-range atomic correlations, we establish the existence of an instantaneous, local orthorhombic structural distortion attributable to nematic fluctuations that persists well into the high-temperature tetragonal phase, at least up to 300 K and likely to significantly higher temperatures. This short-range orthorhombic distortion is correlated over a length scale of about 1 nm at 300 K and grows to several nm as the temperature is lowered toward the long-range structural transition temperature. In the low-temperature nematic state, the local instantaneous structure exhibits an enhanced orthorhombic distortion relative to the average structure with a typical relaxation length of 3 nm. The quantitative characterization of these orthorhombic fluctuations sheds light on nematicity in this canonical iron-based superconductor.