Probing the direct factor for superconductivity in FeSe-Based Superconductors by Raman Scattering
Abstract
The FeSe-based superconductors exhibit a wide range of critical temperature Tc under a variety of material and physical conditions, but extensive studies to date have yet to produce a consensus view on the underlying mechanism. Here we report on a systematic Raman-scattering work on intercalated FeSe superconductors Lix(NH3)yFe2Se2 and (Li,Fe)OHFeSe compared to pristine FeSe. All three crystals show an anomalous power-law temperature dependence of phonon linewidths, deviating from the standard anharmonic behavior. This intriguing phenomenon is attributed to electron-phonon coupling effects enhanced by electron correlation, as evidenced by the evolution of the A1 g Raman mode. Meanwhile, an analysis of the B1 g mode, which probes the out-of-plane vibration of Fe, reveals a lack of influence by previously suggested structural parameters, and instead indicates a crucial role of the joint density of states in determining Tc. These findings identify carrier doping as the direct factor driving and modulating superconductivity in FeSe-based compounds.
- Publication:
-
Physical Review B
- Pub Date:
- August 2019
- DOI:
- 10.1103/PhysRevB.100.060504
- arXiv:
- arXiv:1911.05349
- Bibcode:
- 2019PhRvB.100f0504Z
- Keywords:
-
- Condensed Matter - Superconductivity;
- Condensed Matter - Strongly Correlated Electrons
- E-Print:
- 6 pages, 4 figures