Mott Kondo Insulating Behavior in Iron-Oxychalcogenides

The findings of unconventional high-Tc superconductivity (HTSC) in Fe arsenides and selenides have reinvigorated HTSC research. The outstanding debate over how the normal state gives way to HTSC in cuprates has emerged in discussions on possible HTSC mechanisms in Fe-based superconductors. Does Fe-based HTSC result as a pairing instability of a conventional Landau-Fermi liquid (LFL), or as one of a non-LFL, akin to the cuprates? One possible way to address this important question is to investigate Fe-based materials that exhibit a Mott insulating parent phase as in the cuprates. Here we present a study of such materials. We performed a combined experimental-theoretical investigation of the Fe-oxychalcogenides (FeO\textit{Ch}) series La$_{\mathrm{2}}$O$_{\mathrm{2}}$Fe$_{\mathrm{2}}$O$M_{\mathrm{2}}$ ($M=$S, Se), the latest among the Fe-based materials with the potential to show unconventional high-Tc superconductivity (HTSC).