Here we use angle-resolved photoemission spectroscopy to study superconductivity that emerges in two extreme cases, from a Fermi liquid phase (LiFeAs) and an incoherent bad-metal phase (FeTe0.55Se0.45). We find that although the electronic coherence can strongly reshape the single-particle spectral function in the superconducting state, it is decoupled from the maximum superconducting pairing amplitude, which shows a universal scaling that is valid for all FeSCs. Our observation excludes pairing scenarios in the BCS and the BEC limit for FeSCs and calls for a universal strong coupling pairing mechanism for the FeSCs.
@article{arxiv.1804.07601,
title = {Decoupled Pairing Amplitude and Electronic Coherence in Iron-Based Superconductors},
author = {H. Miao and W. H. Brito and Z. P. Yin and R. D. Zhong and G. D. Gu and P. D. Johnson and M. P. M. Dean and S. Choi and G. Kotliar and W. Ku and X. C. Wang and C. Q. Jin and S. -F. Wu and T. Qian and H. Ding},
journal= {arXiv preprint arXiv:1804.07601},
year = {2018}
}