NSLS-II Friday Lunchtime Seminar

"Local structural symmetry breaking at ambient conditions in FeSe superconductor"

Presented by Robert Koch, Condensed Matter Physics and Materials Science Dept

Friday, October 23, 2020, 12:00 pm — ZoomGov

We report pair distribution function measurements of the iron-based superconductor FeSe above and below the structural transition temperature. Structural analysis reveals a local orthorhombic distortion with a correlation length of about 4 nm at temperatures where an average tetragonal symmetry is observed. The analysis further demonstrates that the local distortion is larger than the global distortion at temperatures where the average observed symmetry is orthorhombic. Our results suggest that the low-temperature macroscopic nematic state in FeSe forms from an imperfect ordering of orbital-degeneracy-lifted nematic fluctuations which persist up to at least 300 K.

Hosted by: Ignace Jarrige

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