1. Nematic response revealed by coherent phonon oscillations in BaFe$_2$As$_2$
- Author
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Lee, Min-Cheol, Kwak, Inho, Lee, Yeongseon, Lee, Bumjoo, Park, Byung Cheol, Wolf, Thomas, Noh, Tae Won, and Kim, Kyungwan
- Subjects
Condensed Matter - Superconductivity ,Condensed Matter - Strongly Correlated Electrons - Abstract
We investigate coherent phonon oscillations of BaFe$_2$As$_2$ using optical pump-probe spectroscopy. Time-resolved optical reflectivity shows periodic modulations due to $A_{1g}$ coherent phonon of $c$-axis arsenic vibrations. Optical probe beams polarized along the orthorhombic $a$- and $b$-axes reveal that the initial phase of coherent oscillations shows a systematic deviation as a function of temperature, although these oscillations arise from the same $c$-axis arsenic vibrations. The oscillation-phase remains anisotropic even in the tetragonal structure, reflecting a nematic response of BaFe$_2$As$_2$. Our study suggests that investigation on the phase of coherent phonon oscillations in optical reflectivity can offer unique evidence of a nematic order strongly coupled to a lattice instability., Comment: 5 pages, 4 figures
- Published
- 2021
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