4 p.m. - 5:15 p.m. Location: SLC 1.102
Dr. Zhiping Yin (Rutgers)
Superconductivity, or the ability to conduct electricity without energy loss, remains one of the most fascinating phenomena in physics for over 100 years. However, our understanding of unconventional superconductivity is still far from complete. The recently discovered iron-based superconductors are another family of unconventional high-temperature superconductors, with second highest superconducting temperature after the copper-oxide based materials. Differing from the copper-oxide superconductors, the multi-band and multi-orbital nature of the iron-based compounds, coupled with strong Coulomb interaction, makes the interplay of the charge, spin, orbital, and lattice degrees of freedom very intriguing, leading to many exotic properties (such as fractional power-law behaviour, spin-orbit separation and orbital anti-phase superconducting pairing) and various competing phases including stripe antiferromagnetic phase, nematic phase, and superconducting phase. Hence it is very challenging to model these materials in either the itinerant weak coupling picture (e.g. band picture) or the localized strong coupling scenario (e.g. t-J models). In this talk, I will discuss their unique properties and present a framework, namely, the combination of density functional theory and dynamical mean field theory, that unifies both itinerant and localized viewpoints and makes first-principles modelling of these materials possible and realistic.