Title: Frustrated Magnetism and Superconductivity in Iron Pnictides and Chalcogenides
Abstract: This talk will provide a brief overview of the field of the iron-based superconductivity (FeSC), and discuss several topical issues. In the beginning of the field, iron pnictides were the focus of attention. More recently, iron chalcogenides have taken the center stage, providing not only a renewed hope for even higher superconducting transition temperatures, but also new puzzles that contain clues to the underlying physics. I will address how the bad-metal properties observed in the normal state of these systems motivate the considerations of frustrated magnetism. I will explore some of the consequences of such considerations. These include quantum criticality; magnetism and its role in driving a nematic order, particularly the enigma case of FeSe; and superconductivity, with an emphasis on how orbital selectivity relieves quasi-degeneracy in the pairing channels and induces an unusual pairing state. These issues will be placed in the context of the overall physics of the FeSCs.