Abstract: In the past several decades, the Hubbard model has been very successful in understanding electronic behaviors in strongly correlated electron systems, and it has many derivatives with the consideration of new degrees of freedom or constrictions. In recently discovered iron-based high-Tc superconductors, a multi-orbital Hubbard model is usually involved. The resultant orbital selective Mott physics was successful in understanding the uncommon electronic behaviors in the proximity to 3d6 electronic configuration in relevant materials.
In this seminar, I will talk about our recent exploration of electron correlation effects in heavily electron-doped, cobalt-based materials and report a newfound continent of electron correlation that was not predicted in the existing phase diagram. Our observation of flat-band magnetism and helical magnetic order in nickel-doped SrCo2As2 may shed light on the ongoing efforts of understanding exotic physics in flat-band systems.