While a predictive theory for unconventional superconductivity in Fe-based superconductors remains elusive, an extensively debated aspect is the interaction between phonons and strongly correlated electrons, and its potential role in the pairing mechanism. Here, through the combination of first principles dynamical mean field theory calculations and epitaxial growth of the single-layer FeX (X=Se, S, Te) on SrTiO3 (STO)(001) substrate, which facilitates the controlled distortion of the FeX4 tetrahedron, we demonstrate an unique superconducting dome where the superconducting gap peaks at a `magic' angle of the FeX4 tetrahedron and the electron-phonon coupling (EPC) for the A1g mode is maximized for the FeSe film. Our findings uncover a significant role of electronic correlations in strengthening Cooper pairing in unconventional superconductors by enhancing EPC.
@article{arxiv.2506.22435,
title = {Correlation Enhanced Electron-Phonon Coupling in FeSe/SrTiO$_3$ at a Magic Angle},
author = {Qiang Zou and Antik Sihi and Basu Dev Oli and Mercè Roig and Daniel Agterberg and Michael Weinert and Lian Li and Subhasish Mandal},
journal= {arXiv preprint arXiv:2506.22435},
year = {2025}
}