We combine transport, angle-resolved photoemission spectroscopy and scanning tunneling spectroscopy to investigate several low energy manifestations of the Hund coupling in a canonical FeSC family Li(Fe,Co)As. We determine the doping dependence of the coherent-incoherent crossover temperature and the quasi-particle effective mass enhancement in the normal state. Our tunneling spectroscopy result in the superconducting state supports the idea that superconductivity emerging from Hund's metal state displays a universal maximal superconducting gap vs transition temperature (2Δmax/kBTc) value, which is independent of doping level and Tc.
@article{arxiv.2011.11475,
title = {The Hund's Superconductor Li(Fe,Co)As},
author = {H. Miao and Y. L. Wang and J. -X. Yin and J. Zhang and S. Zhang and M. Z. Hasan and R. Yang and X. C. Wang and C. Q. Jin and T. Qian and H. Ding and H. -L. Lee and G. Kotliar},
journal= {arXiv preprint arXiv:2011.11475},
year = {2021}
}