We perform a combined experimental-theoretical study of the Fe-oxychalcogenides (FeOCh) series La2O2Fe2O\emph{M}2 (\emph{M}=S, Se), which is the latest among the Fe-based materials with the potential \ to show unconventional high-Tc superconductivity (HTSC). A combination of incoherent Hubbard features in X-ray absorption (XAS) and resonant inelastic X-ray scattering (RIXS) spectra, as well as resitivity data, reveal that the parent FeOCh are correlation-driven insulators. To uncover microscopics underlying these findings, we perform local density approximation-plus-dynamical mean field theory (LDA+DMFT) calculations that unravel a Mott-Kondo insulating state. Based upon good agreement between theory and a range of data, we propose that FeOCh may constitute a new, ideal testing ground to explore HTSC arising from a strange metal proximate to a novel selective-Mott quantum criticality.
@article{arxiv.1501.00332,
title = {Mott-Kondo Insulator Behavior in the Iron Oxychalcogenides},
author = {B. Freelon and Yu Hao Liu and Jeng-Lung Chen and L. Craco and M. S. Laad and S. Leoni and Jiaqi Chen and Li Tao and Hangdong Wang and R. Flauca and Z. Yamani and Minghu Fang and Chinglin Chang and J. -H. Guo and Z. Hussain},
journal= {arXiv preprint arXiv:1501.00332},
year = {2015}
}