Abstract
We report on temperature-dependent pair distribution function measurements of , an iron-based superconductor system that contains a magnetic phase with reentrant tetragonal symmetry, known as the magnetic phase. Quantitative refinements indicate that the instantaneous local structure in the phase comprises fluctuating orthorhombic regions with a length scale of , despite the tetragonal symmetry of the average static structure. Additionally, local orthorhombic fluctuations exist on a similar length scale at temperatures well into the paramagnetic tetragonal phase. These results highlight the exceptionally large nematic susceptibility of iron-based superconductors and have significant implications for the magnetic phase and the neighboring and superconducting phases.
- Received 9 June 2017
DOI:https://doi.org/10.1103/PhysRevLett.119.187001
© 2017 American Physical Society