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Ultrafast Quasiparticle Dynamics and Electron-Phonon Coupling in high-Tc iron-based superconductor (Li0.84Fe0.16)OHFe0.98Se

Date:09-09-2020 Print

So far no consensus has been reached on the underlying physics for the unconventional superconductivity in iron-based compounds, including the FeSe- and FeAs-based, as well as FeSe-monolayer systems. Significantly, the driving force for the electron pairing remains an issue of hot debate.

Recently, Professor Jimin Zhao and his PhD student Qiong Wu, et al. investigated the quasiparticle ultrafast dynamics of FeSe-based high-Tc (Li0.84Fe0.16)OHFe0.98Se single crystal by using ultrafast optical spectroscopy. They obtained the electron-phonon coupling (EPC) strength λA1g = 0.22 ± 0.04 directly from the experiment. Also obtained are the EPC strengths for two other iron-based superconductors with different SC transition temperature Tc, Fe1.01Se0.2Te0.8 and Fe1.05Se0.2Te0.8. Importantly, they found that almost all the optimally doped iron-based superconductors (including the FeSe-based, FeAs-based, and Monolayer FeSe systems) share a universal positive correlation between Tc and the EPC strength (λA1g or λ), shown in the figure. This result indicates that the EPC plays an important role in the electron pairing. The work entitled “Ultrafast Quasiparticle Dynamics and Electron-Phonon Coupling in high-Tc iron-based superconductor (Li0.84Fe0.16)OHFe0.98Se” is recently published in Chinese Physics Letters (Express Letter) 37, 097802 (2020). The results reveal the consonant physics with the isotope effect observed in FeAs-based superconductors by Professor Xianhui Chen’s team in the University of Science and Technology of China [Nature 459, 64 (2009)].

This work is collaborated with Professor Zhongxian Zhao, Professor Xiaoli Dong, Dr. Huaxue Zhou, and Professor Fang Zhou, and is financially supported by the NNSFC, the MOST, and the CAS.

Link to the paper: http://cpl.iphy.ac.cn/article/10.1088/0256-307X/37/9/097802

Universal positive correlation between Tc and the EPC strength λA1g (λ) in iron-based superconductors. (Image by Institute of Physics)

Contact:
Institute of Physics
ZHAO, Jimin
Email:jmzhao@iphy.ac.cn

Key word:
Iron-based superconductor; Electron-phonon coupling (EPC); Ultrafast dynamics; Pairing glue; Superconductivity

Abstract:
Ultrafast optical spectroscopy experiment finds that a positive correlation between the SC Tc and λA1g holds universally among all known categories of Iron-based superconductors, which indicates the important role of EPC in the superconductivity of iron-based superconductors.