Correlation-Enhanced Electron-Phonon Coupling and Tc in (LiOH)FeSe Superconductors

Iron-based superconductors serve as an important platform for investigating unconventional superconductivity. Among them, (LiOH)-intercalated FeSe structures exhibit a significantly enhanced superconducting transition temperature (Tc) compared to bulk FeSe. Despite extensive research, the underlying mechanisms driving superconductivity and the enhanced Tc remain elusive. In this study, we explore the possibility that the elevated Tc can be explained by a correlation-enhanced electron-phonon coupling mechanism, as described by Bardeen’s deformation potential theory as well as the Allen-Dynes formula and Eliashberg equation. Our combined density functional theory and dynamical mean-field theory (DFT+DMFT) calculations indicate that electronic correlation effects can significantly enhance the electron-phonon coupling and the resulting Tc in (LiOH)FeSe. This enhancement is attributed to both the FeSe superconducting layer and the (LiOH) spacing layer. Our approach offers a new route for the theoretical exploration of higher-Tc superconductors.